Developed a polymer electrolyte that quadruples power generation efficiency

The research team presented a design strategy for precisely controlling polarity, a key property of triboelectric materials. The key to this research is to structurally adjust the polarity direction using polyelectrolytes and achieve improved long-term durability.

The findings are published in the journal Advanced Materials. The team includes Professor Ju-Hyuck Lee of DGIST’s School of Energy Science and Engineering and others, working with Wonho Lee’s team at Kumo National Institute of Technology.

This frictional power generation technology generates electricity through friction and is attracting attention as it can generate electricity without using batteries. However, traditional ionic liquid-based materials have faced difficulties in commercialization due to problems such as leakage, environmental instability, and limited durability.

To address these limitations, the research team designed a polymer electrolyte with ions anchored to polymer chains and proposed a new platform concept in which this material can be used to precisely control triboelectric polarity in the desired direction. This approach not only improves output performance but also increases material design flexibility.

The research team synthesized a series of polyelectrolytes with either cationic or anionic properties and comparatively analyzed their performance. As a result, the cationic polymer P(MA-A⁺20)TFSI⁻ exhibited an output voltage of 83V, approximately twice that of the conventional material (PMA), and the anionic polymer P(SS⁻10)Na⁺ achieved an output voltage of 34V, four times that of the conventional material (PS). These experiments demonstrated that the triboelectric polarity (positive/negative) can be tuned depending on the polymer structure, and that the output performance can be further tuned by controlling the ionic composition ratio.

Additionally, the ionic anchor structure within the polymer chain minimizes charge loss due to unwanted ion migration and ensures excellent thermal stability, maintaining stable output for more than a week even at 60 °C. In contrast, a conventional polymer-ionic liquid mixture (PMMA + 10IL) showed a power reduction of about 27% under the same conditions. These results clearly demonstrate the superiority of polyelectrolyte-based materials.

Professor Ju-Hyuck Lee of DGIST said, “This research is significant in that it not only improves performance but also presents a new concept of controlling friction polarity through the structural design of polymers.We hope that this approach will provide a new direction for the development of next-generation energy harvesting devices.”