Engineers Develop High-Performance 3D Microbattery
Ilan Mester posted on May 14, 2015 |
Source: University of Illinois Urbana-Champaign

Research engineers have created a high-performance 3D microbattery that is ideal for large-scale on-chip integration with microelectronic devices. How? The short answer is simple: by integrating 3D holographic lithography with 2D photolithography.  

“This 3D microbattery has exceptional performance and scalability, and we think it will be of importance for many applications,” explained Paul Braun, a materials science and engineering professor at the University of Illinois Urbana-Champaign. “Micro-scale devices typically utilize power supplied off-chip because of difficulties in miniaturizing energy storage technologies.”

He added: “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.”

Utilizing 3D holographic lithography 

The complexity of 3D electrodes makes it difficult to develop these types of batteries. That’s why the researchers had to be creative.

“We utilized 3D holographic lithography to define the interior structure of electrodes and 2D photolithography to create the desired electrode shape,” added graduate student Hailong Ning. “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.”

Lighting an LED with a 0.5 mA current
Lighting an LED with a 0.5 mA current. Source: University of Illinois Urbana-Champaign

The engineers utilized a 3D holographic patterning technique in which a number of optical beams interfere inside the photoresist, which results in a 3D structure. The battery boasts porous electrodes that help rapidly transport its electrons and ions.

Using standard photoresist processing 

“Although accurate control on the interfering optical beams is required to construct 3D holographic lithography, recent advances have significantly simplified the required optics, enabling creation of structures via a single incident beam and standard photoresist processing,” said fellow MatSE professor John Rogers. “This makes it highly scalable and compatible with microfabrication.”

William King, a professor of mechanical science and engineering, added: “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.”

For more information, visit the University of Illinois Urbana-Champaign’s website.

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