This may all be about to change though, thanks to researchers at at the University of Illinois at Urbana-Champaign. The research team, consisting of Hailong Ning, James H. Pikul, Runyu Zhang, Xuejiao Li, Sheng Xu, Junjie Wang, John A. Rogers, William P. King, and Paul V. Braun have discovered a way of 3D printing lithium-ion microbatteries which can actually be placed directly onto small chips.
The process is one which combines 3D holographic lithography with the more conventional 2D photolithography (a process similar to methods used to make printed circuit boards) to create mesostructured electrodes. All of the details of this research have been published in a paper titled “Holographic Patterning of High Performance on-chip 3D Lithium-ion Microbatteries,” appearing in Proceedings of the National Academy of Sciences.
“Due to the complexity of 3D electrodes, it is generally difficult to realize such batteries, let alone the possibility of on-chip integration and scaling,” explained Hailong Ning, a MatSE graduate student and first author of the article. “In this project, we developed an effective method to make high-performance 3D lithium-ion microbatteries using processes that are highly compatible with the fabrication of microelectronics. We utilized 3D holographic lithography to define the interior structure of electrodes and 2D photolithography to create the desired electrode shape. 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.”
For traditional microscale devices, power is supplied off-chip because of the extreme difficulties in miniaturizing the energy storage technology. These batteries, however, suddenly become extremely desirable for applications which include microscale wireless sensors, portable and implantable medical devices, autonomous micro electromechanical systems (MEMS)-based acutuators, and distributed monitors, among many other things.
“For many of the applications, high energy density, high power density (charge and/or discharge), or some combination of high energy and power densities is required, all characteristics which can be difficult to achieve in a microbattery due to size and footprint restrictions, and process compatibilities with the other steps required for device fabrication,” the report reads.
“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,” explained William King, a professor of mechanical science and engineering, and a co-author of this paper.
The researchers were able to demonstrate these batteries in use when connected to an LED. Even though the microbattery in the demonstration only had a volume of 0.04 cubic mm and a capacity of just 0.83μAh, it was able to easily power the LED at least 200 separate times. Quite impressive for a battery of this size. The video below shows the full charge-discharge cycle.
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