A New Microbattery Stores Four Times the Energy With Its Own Packaging

Breaking through engineering limitations.
Brad Bergan
The high-density microbattery, resting on a tiny plant.University of Pennsylvania

Sometimes, big power comes in small packages.

Scientists have conceived of a new design for tiny batteries, overcoming a fundamental problem by developing far denser cathodes capable of being "electroplated" directly onto thin metal foils, according to a recent study published in the journal Advanced Materials.

Crucially, these new tiny batteries can store four times the energy of conventional (tiny) ones.

A denser cathode material quadrupled a microbattery's energy storage

This is masterful employment of one of the most interesting frontiers of next-gen battery research, which emphasizes the use of structural components to store energy. The new microbattery is so light, it could be carried by insects, and was researched by engineers at the University of Pennsylvania, who are analyzing various designs for compact yet durable batteries that can power unconscionably small wearables, in addition to other electronic devices. But to protect the devices from damage via water, oxygen, and old-fashioned impacts, batteries are sheltered in casing that weighs them down, and adds in bulkiness, which doesn't help electrochemical performance.

This is why the engineers broke with the conventional ultra-thin electrodes typically used to rapidly transport electrons and ions: to avoid the slim profile that limits the amount of chemicals they may contain, which, in turn, puts a ceiling on the maximum energy that can be stored. Cathodes are one of two electrodes in a battery, and usually are composed of crushed particles smashed together such that a porous structure is created, allowing for air gaps. This affects ion speed as they zip through the battery. The scientists solved this issue by turning to a far denser cathode material that enabled an "electroplating" directly onto the thin metal foils. And the thin metal foils perform a dual function, both as a protective layer and energy storage material.

The new microbattery weighs about the same as two grains of rice

"We essentially made current collectors that perform double duty," said James Pikul, leader of the study, in a New Atlas report. "They act as both an electron conductor and as the packaging that prevents water oxygen from getting into the battery." The researchers also said their new microbattery design aligns the cathode's "atomic highways" in a way that enables lithium ions to progress rapidly through the cathode, arriving after a direct journey to the device. Since ions don't have to move around the air pockets, the cathode can be built into a much thicker material without sacrificing on this crucial property, which multiplies how much (in terms of volume) energy-storing chemicals it may hold, by two.

This enabled the engineers to construct a microbattery with an energy density that is four times what we see in conventional, high-tech battery designs. And their microbattery weighs roughly the same as two grains of rice, with the power density of a battery 100 times its size. The new device will see a litany of future applications, including wearables, medical implants (that last longer), flying robots, and the growing multitude of wireless devices that are rapidly filling the social and technological world of our increasingly advanced society. While the scientists will go on improving the performance of this novel microbattery, we can add it to the list of crucial parts of the devices that will transform our world into a futuristic techno-society beyond our wildest dreams.

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