Development of free stretchable and printable
A Korean research team has developed a flexible, mechanically deformable and expandable lithium battery that can be used in the development of wearable devices, and examined the feasibility of the battery by printing them on clothing surfaces. The research team, led by Dr. Jeong Gon Son of the Soft Hybrid Materials Research Center of the Korea Institute of Science and Technology (KIST); Chairman: Seok-Jin Yoon), announced that they have developed a lithium battery in which all materials including anode, cathode, current collector, electrolytes and encapsulant are expandable and printable . The lithium battery developed by the team has high capacity and free-form characteristics suitable for mechanical deformation.
Due to the increasing demand for high performance wearable devices such as smart wristbands, implantable electronic devices such as pacemakers, and soft wearable devices for use in the realistic metaverse, the development of a soft and expandable battery like the human skin and organs arouse interest.
The hard inorganic electrode of a conventional battery comprises the majority of the battery’s volume, making it difficult to stretch. Other components, such as the separator and the current collector for pulling and transferring charges, also need to be expandable, and the problem of liquid electrolyte leakage should also be solved.
To improve extensibility, the research team avoided using materials as had been done in other studies that were not needed for energy storage, such as rubber. Then, a new soft and stretchy organic gel material was developed and applied based on the existing binder material. This material firmly holds the active electrode materials in place and facilitates the transfer of ions. In addition, a conductive ink has been manufactured using a material with excellent stretching and gas barrier properties to serve as a current-collecting material that transfers electrons and an encapsulant that can work stably even at high voltage. and in various deformed states without swelling due to absorption of electrolytes.
The battery developed by the team is also capable of incorporating existing lithium-ion battery materials, as they exhibit excellent energy storage density (~2.8 mWh/cm2) of a level similar to that of commercially available lithium-ion batteries at supply voltage. 3.3V or more. All constituent components of the team’s expandable lithium-ion battery have the mechanical stability to maintain their performance even after pulling the battery 1,000 times or more, high expandability of 50% or more, and long-term stability in the air.
Additionally, the research team directly printed the electrode and current collector materials they had developed on either side of a spandex arm warmer and applied a stretch encapsulant to the material, demonstrating the ability to print an expandable high voltage organic battery directly on Clothing. Using the resulting battery, the research team was able to continuously power a smartwatch, even when it was put on, taken off, or stretched.
KIST’s Dr. Son said his team has developed expandable lithium-ion battery technology that provides both structural freedom through the battery’s free-form configuration allowing it to be printed on materials such as fabrics , and material freedom due to being able to use existing lithium-ion battery materials, in addition to stretch stability that allows for high energy density and mechanical deformation. He also said that the expandable energy storage system developed by his team should be applicable to the development of various wearable or body-attachable devices.
This study was supported by the Mid-Career Research Program of the National Research Foundation of Korea, and the KIST Institutional Program and K-Lab Program funded by the Ministry of Science and ICT (Minister: Hye-Sook Lim ). The research results have been published in ACS Nano (IS: 15.881).
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Intrinsically expandable and printable lithium-ion battery for free-form configuration
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