Researchers create microbattery that could power insect-sized robots

The battery resolves a longstanding technological issue that no other battery design has ever addressed.
Loukia Papadopoulos
Depiction of microrobots in a hazardous environment.jpg
Depiction of microrobots in a hazardous environment.

Alex David Jerez Roman, Beckman institute, UIUC 

Micro batteries have the incredible potential to power microdevices, microrobots, and implantable medical devices. However, up to recently they have not been very efficient as they lacked power.

Now, the University of Illinois Urbana-Champaign researchers has created a high-voltage microbattery unparalleled by any existing battery design, according to a press release by the institution published on Thursday.

Unlocking the potential of smaller devices

“We need powerful tiny batteries to unlock the full potential of microscale devices, by improving the electrode architectures and coming up with innovative battery designs,” Material Science and Engineering Professor Paul Braun (Grainger Distinguished Chair in Engineering, Materials Research Laboratory Director) explained.

One problem that the researchers had to overcome was that as batteries become smaller, the packaging dominates the battery volume and mass while the electrode area becomes smaller, resulting in significant reductions in energy and power.

To overcome this issue, the team developed novel packaging technology that used the positive and negative terminal current collectors as part of the packaging itself.

The result was small microbatteries that still produced a high operating voltage.

“To date, electrode architectures and cell designs at the micro-nano scale have been limited to power-dense designs that came at the cost of porosity and volumetric energy density. Our work has been successful to create a microscale energy source that exhibits both high power density and volumetric energy density,” said Arghya Patra (Graduate Student, MatSE, MRL, co-first author).

The development bridges gap

The researchers noted that the development brings together many sectors and industries.

“Our work bridges the knowledge gap at the intersection of materials chemistry, unique materials manufacturing requirements for energy-dense planar microbattery configurations, and applied nano-microelectronics that require a high-voltage, on-board type power source to drive microactuators and micromotors,” Dr. Sungbong Kim (Postdoc, MatSE, currently assistant professor at Korea Military Academy, co-first author) added.

In terms of applications, one crucial one could be powering insect-size microrobots to obtain valuable information during natural disasters, search and rescue missions, and in hazardous environments where direct human access is impossible. 

Co-author James Pikul (Assistant Professor, Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania) pointed out that “the high voltage is important for reducing the electronic payload that a microrobot needs to carry.”

“This means that these batteries enable system-level improvements beyond their energy density enhancement so that the small robots can travel farther or send more critical information to human operators,” Pikul further concluded.

Batteries as small as 'smart dust'

Researchers have been working on microbatteries for a long time and have had success with the devices before producing batteries small enough to be used as “smart dust.”

In August of 2022, a team of researchers at the Chemnitz University of Technology in Germany developed microbatteries the size of rice grains. They claimed their invention could be used in the future to power advanced IoT (Internet of things) applications like smart microsensors and millimeter-scale computing devices through something they called “smart dust,” a highly advanced version of IoT.

This type of "dust" would consist of micro and nano-scale devices that would be distributed everywhere, including cities, factories, and forests. They would serve to monitor the different changes happening around us in real time.

 The study was first published in Cell Reports Physical Science.

Study abstract:

Accessing high voltages (>9 V) and high power density in microbatteries with volumes below ∼0.25 cm3 is challenging. At such scales, energy density and voltage are highly constrained by packaging and serial integration of cells. Here, we demonstrate hermetically sealed, durable, compact (volume ≤ 0.165 cm3) batteries with low package mass fraction (10.2%) in single- (∼4 V), double- (∼8 V), and triple-stacked (∼12 V) configurations with energy densities reaching 990 Wh Kg−1 and 1,929 Wh L−1 (triple-stacked battery discharged at C/10) and high power density for continuous and pulsed discharge (∼124 mW cm−2 for triple-stacked battery at C/2 continuous discharge, ∼75 mW cm−2 for double-stacked battery at 2C pulsed discharge). We achieve the high voltage-power-energy density landscape by using current collectors as the package and serial stacking of bifancial dense electrodeposited LiCoO2 cathode, Li-metal anode electrodes. Our microbatteries power wireless communication electronics, motors, and actuators, paving the way toward highly functional microdevices.

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