Flexoelectricity for green energy batteries

便携式电子产品和传感器等创新技术的蓬勃发展正在增加对可再生能源的需求。为了满足这一需求，最近提出了摩擦电纳米发电机（TENG）。TENG是一种绿色能量收集装置，通过耦合摩擦电和静电感应将机械能转换为电能。它们可以为电池充电，并为用于广泛应用的自供电电子设备和传感器提供能量。这种多功能性使TENG成为替代化石能源和推动绿色转型的关键设备。然而，它们的应用仍然面临限制，因为一旦达到电子饱和点，电力输出开始下降。EXCITON旨在通过利用机电效应（如挠曲电）来提高TENG的性能。柔性电性是指由应变梯度引起的电极化的产生，其在纳米级和柔性2D和聚合物材料中很大，广泛用于TENG制造。这些效应在摩擦接触中强烈增强，其中可以利用高不均匀应力来增加电输出和TENG性能。事实上，最近有人提出，挠曲电驱动摩擦电化。EXCITON提供了对柔印和摩擦电之间相互作用的基本理解，旨在确定一种永久改善TENG性能的合理方法。我将评估不均匀变形对2D和聚合物材料的摩擦充电的影响，结合从头算DFPT和实验摩擦和KPFM测量这些材料的机电和摩擦电性能。理论/实验相结合的方法将允许建立一个新的协议，在该领域的研究，并将构成第一步的结果的应用。

The booming development of innovative technologies, such as portable electronics and sensors, is increasing the demand for renewable power supplies. To meet this demand triboelectric nanogenerators (TENGs) have been recently proposed. TENGs are green energy-harvesting devices that convert mechanical energy into electricity by coupling triboelectricity and electrostatic induction. They can charge batteries and provide energy to self-powered electronics and sensors used for a wide range of applications. This versatility makes TENGs key devices to replace fossil energy and drive the green transition.Their application, however, still faces limitations because once the electronic saturation point is reached the electric output starts to decrease. EXCITON aims at enhancing TENGs performances by exploiting electromechanical effects such as flexoelectricity. Flexoelectricity refers to the generation of electric polarization caused by strain gradients, which are large at the nanoscale and in flexible 2D and polymeric materials, widely used in TENGs fabrication.These effects are strongly enhanced in tribological contact, where high non-uniform stresses can be exploited to increase the electric output and TENGs performance. Indeed, it has been recently suggested that flexoelectricity drives triboelectrification. Providing a fundamental understanding of the interplay between flexo and triboelectricity, EXCITON aims to determine a sound method to permanently improve TENGs performances. I will evaluate the effect of non-uniform deformations on the tribocharging of 2D and polymeric materials by combining ab-initio DFPT and experimental tribometric and KPFM measurements of the electromechanical and triboelectric properties of these materials. The combined theoretical/experimental approach will allow to establish a new protocol for the studies in the field and will constitute a first step towards the application of the outcomes.