Surface modification for prolonging the lifetime of triboelectric nanogenerators enhanced by corona discharge

Triboelectric nanogenerators (TENGs) have emerged as promising energy harvesting devices due to their low cost, flexible design, and ability to convert low-frequency mechanical energy into electricity. However, their practical application remains limited by low surface charge density and poor long-term stability. To address the former, corona discharge treatment has been widely employed to inject high-energy negative charges into polymer surfaces, significantly enhancing initial output voltage. Nevertheless, the effectiveness of corona discharge is short-lived, as the injected charges dissipate rapidly due to recombination with atmospheric positive ions and chemical degradation induced by oxygen and moisture. This temporal degradation directly causes a decline in output voltage over time, severely limiting long-term viability of TENG. To address the issue of dissipation of corona-injected charges, which leads to a gradual decline in output performance, we introduce a surface encapsulation strategy. In this approach, a thin polydimethylsiloxane (PDMS) overlayer is applied to the corona-treated films to suppress charge recombination and surface degradation. This overlayer functions as a physical barrier, effectively suppressing both electrostatic recombination and chemical decay. Experimental results confirm that this approach greatly improves charge retention in both pure PDMS and TiO 2 /PDMS composite films. Specifically, voltage retention increased from around 25 to 85% in coated pure PDMS films after 60 days. In TiO 2 composites with inherently higher charge densities, retention remained as high as 72.6%. This study demonstrates that the synergistic combination of corona discharge and PDMS coating offers a robust strategy to achieve both high initial performance and long-term operational stability, paving the way for durable and efficient TENG devices in real-world energy harvesting applications.