3-D microbattery suitable for large-scale on-chip integration

 

Tue, 05/12/2015 - 8:18am Rick Kubetz, University. of Illinois, Urbana-Champaign   Image of the holographically patterned microbattery.By combining 3-D holographic lithography and 2-D photolithography, researchers from the Univ. of Illinois at Urbana-Champaign have demonstrated a high-performance 3-D microbattery suitable for large-scale on-chip integration with microelectronic devices. "This 3-D microbattery has exceptional performance and scalability, and we think it will be of importance for many applications," explained Paul Braun, a professor of materials science and engineering at Illinois. "Micro-scale devices typically utilize power supplied off-chip because of difficulties in miniaturizing energy storage technologies. A miniaturized high-energy and high-power on-chip battery would be highly desirable for applications including autonomous microscale actuators, distributed wireless sensors and transmitters, monitors and portable and implantable medical devices." "Due to the complexity of 3-D electrodes, it is generally difficult to realize such batteries, let alone the possibility of on-chip integration and scaling. In this project, we developed an effective method to make high-performance 3-D lithium-ion microbatteries using processes that are highly compatible with the fabrication of microelectronics," stated Hailong Ning, a graduate student in the Dept. of Materials Science and Engineering and first author of the article appearing in Proceedings of the National Academy of Sciences. "We utilized 3-D holographic lithography to define the interior structure of electrodes and 2-D photolithography to create the desired electrode shape." Ning added. "This work merges important concepts in fabrication, characterization and modeling, showing that the energy and power of the microbattery are strongly related to the structural parameters of the electrodes such as size, shape, surface area, porosity and tortuosity. A significant strength of this new method is that these parameters can be easily controlled during lithography steps, which offers unique flexibility for designing next-generation on-chip energy storage devices." Enabled by a 3-D holographic patterning technique—where multiple optical beams interfere inside the photoresist creating a desirable 3-D structure—the battery possesses well-defined, periodically structured porous electrodes, that facilitates the fast transports of electrons and ions inside the battery, offering supercapacitor-like power. "Although accurate control on the interfering optical beams is required to construct 3-D holographic lithography, recent advances have significantly simplified the required optics, enabling creation of structures via a single incident beam and standard photoresist processing. This makes it highly scalable and compatible with microfabrication," stated John Rogers, a professor of materials science and engineering, who has worked with Braun and his team to develop the technology. "Micro-engineered battery architectures, combined with high energy material such as tin, offer exciting new battery features including high energy capacity and good cycle lives, which provide the ability to power practical devices," stated William King, a professor of mechanical science and engineering, who is a co-author of this work. Source: University. of Illinois, Urbana-Champaign