New Re-Attachable & Flexible “Sticker-Type” Rechargeable Batteries

Re-attachable and flexible rechargeable batteries available to use in next-generation flexible/wearable devices.
Credit: Korea Institute of Energy Research (KIER)

A joint research team from KIER, KAIST, PNU, NTU develops a high-performance re-attachable sticker-type energy storage device. The research findings were published in the world’s renowned Chemical Engineering Journal.

Dr. Yoon Hana at Energy Conversion & Storage Materials Laboratory of Korea Institute of Energy Research (KIER, President Kim Jong-nam), Professor Kim Young-Jin (Dept. of Mechanical Engineering, Korea Advanced Institute of Science and Technology) and Professor Kim Seungchul (Dept. of Optics and Mechatronics Engineering, Pusan National University) jointly developed ‘re-attachable micro-supercapacitors (MSCs)* using highly swollen laser-induced-graphene electrodes’ and their research findings were listed in Chemical Engineering Journal*, one of the world-renowned in the field.

* MSCs are thin-film based ultra-thin supercapacitors that are getting much attention as they are more stable with higher power and energy densities compared to Li thin-film batteries.

Chemical Engineering Journal is considered as one of the best international journals in the chemical engineering sector (published by Elsevier, SCI I.F. 8.355)

As demands for lighter and smaller wearable devices and high functional IoT gadgets rise, there is a growing need for new technologies for power collection, storage, management. Wearable devices and IoT products are increasingly applied to various sectors of the society these days. Hence, researchers are actively carrying out R&D activities to develop energy storage devices with additional functions besides power supply.

Preconditions of wearable energy storage devices are that they should be able to change their forms along with changing shapes of the human body and movements while being flexible, safe to use, and providing excellent durability. The conventional batteries were not flexible as they were developed to have a cylindrical, prismatic, or pouch type base structure and had limited energy densities. So, they had some limitations to be applied to next-generation products such as wearable devices or micro devices that require high flexibility, portability, and areal or volumetric energy densities.

In the past, R&D efforts to develop energy storage devices for wearable devices were mostly put on Li thin-film batteries. Li thin-film microbatteries, which are widely and commercially available power sources for microelectronics, suffer from short life cycles, abrupt failures, unstable low-temperature kinetics, and pose safety concerns when associated with lithium.

Recently, MSCs are gaining high attention as next-generation energy storage devices to replace Li thin-film batteries. In principle, the supercapacitors were semi permanent to use and had many benefits such as high power densities (10 times more compared with lithium ion batteries), stability, efficiency and fast charge/discharge rates. However, their scope of use was somewhat limited to certain areas due to a low energy density per load (which was estimated as 1/10 of Li batteries). Compared to supercapacitors, MSCs have a significantly higher power density than lithium batteries and energy densities are similar or even higher than their rivals. Hence, they are considered as an alternative for ultra-thin high-performance energy storage devices.

The research team successfully developed sticker-type flexible MSCs that had a flexible structure and can be attached everywhere on objects or surfaces by using ultrashort-pulse-lasers.

Ultrashort-pulse laser can instantly generate strong intensity to make highly swollen graphene electrodes. By impregnating adhesive polymer composites to the inside of highly swollen graphene, researchers were able to develop sticker-type MSCs with excellent electrodes performance and durability while maintaining adhesiveness.

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