Packaging-free design quadruples microbatteries’ energy density

With wireless-enabled electronics becoming smaller and more ubiquitous, their designers must constantly find ways for batteries to store more power in less space. And because these devices are also increasingly mobile—in the form of wearables, robots and more—those batteries must be lighter while still being able to withstand the bumps and bruises of everyday life. Worse still, energy density gets exponentially harder to improve upon as a battery gets smaller, partially because larger portions of a battery’s footprint must be devoted to protective packaging.

Dandelion head for scale with a tiny microbattery resting on top of it.
Weighing about as much as two grains of rice but with the energy density of a much larger, heavier battery, the researchers’ packing-free design could enable a host of otherwise impossible electronics. (Image: Penn Engineering Today)

With that challenge in mind, new research from the School of Engineering and Applied Science has shown a new way to build and package microbatteries that maximizes energy density even at the smallest sizes.

The researchers’ key developments were a new kind of current collector and cathode that increase the fraction of materials that store energy while simultaneously serving as a protective shell. This reduces the need for nonconductive packaging that normally protects a battery’s sensitive internal chemicals.

“We essentially made current collectors that perform double duty,” says James Pikul, assistant professor in the Department of Mechanical Engineering and Applied Mechanics and a leader of the study. “They act as both an electron conductor and as the packaging that prevents water and oxygen from getting into the battery.”

The study is published in the journal Advanced Materials.

Read more at Penn Engineering Today.