Increasing Freedom in Designing Batteries
Professor Kim Il-doo's research team at Korea Advanced Institute of Science and Technology (KAIST) has developed a technology that can dramatically increase the freedom of battery design, in cooperation with Professor Jennifer A. Lewis’s team of Harvard University.
Using 3D printing technology, the KAIST-Harvard joint research team succeeded in freely manufacturing the shape of the battery in the desired structure, including the ring shape and letter shapes like capital letters H and U. In addition, the team collaborated with Dr. Choi Young-min’s team of the Korea Research Institute of Chemical Technology to apply a 3D printing battery to a small wearable optical sensor ring.
Current battery configurations are limited to circular or rectangular structures optimized for coin cell or pouch cell manufacture. In the case of small-sized electronic devices with different designs, the battery storage device occupies most of the volume. Therefore, in order to utilize the space efficiently, a technique that allows unrestricted changes of the shape of the battery is required.
The team has introduced an environmentally friendly water-based zinc-ion battery system to make batteries with unrestricted design. Using zinc ion (Zn2 +) instead of lithium ion as a charge carrier, this system uses water as a part of the electrolyte and is safer than conventional lithium secondary batteries, which use highly flammable organic solvents as electrolytes.
The organic solvent causes deterioration of the battery when exposed to moisture and oxygen, which is one of the factors that make the manufacturing process of the lithium secondary battery difficult. The research team has introduced water-based zinc rechargeable battery, which is stable in moisture and oxygen in the atmosphere, allowing manufacture under more convenient atmospheric conditions.
The KAIST research team manufactured a carbon fiber current collector using electrospinning technology to design the anode that can be cut in a free form and is capable of rapid charging and discharging. Then, the team made a current collector integrated anode by uniformly coating polyaniline-conductive polymers with high electrochemical activity on the carbon fiber surface.
The polyaniline-based anode made of a thin fiber with a 3D structure showed a very fast charging rate of charging 50% in 2 minutes and can be easily cut without loss of active material. Based on these characteristics, manufacture of various forms of battery is expected to become possible.
Professor Kim said, "Zinc secondary batteries using water-soluble electrolytes can be assembled in a regular atmospheric environment for battery packaging, and 3D printing can be used to easily produce customized battery packs that meet customers’ needs."
"The batteries are highly likely to be utilized as power devices that fit the appearance of microminiature robots or as storage devices for uniquely designed compact electronic devices," he added.
The study was published in the December issue of the international journal in the field of material science, ACS Nano.