Bionic wood-inspired structure enables aerogel film triboelectric material with humidity adaptation

Abstract

The water molecules adhering to the surface of the triboelectric layer will take away the surface charge when traditional triboelectric nanogenerators (TENGs) operate in the high-humidity environment, resulting in a reduction in triboelectric performance, which significantly constrains the advancement of TENGs. Herein, a green triboelectric material of chitosan/polyvinyl alcohol longitudinal aerogel film (CP-LAF) with excellent humidity adaptation and triboelectric properties (9 cm2, 214 V, 18.25 μA) was prepared by a process of directional freeze-drying assisted mechanical compression with the idea from the anisotropic structure of natural wood. The triboelectric properties of TENGs are enhanced by their layered-ordered porous structure and rough surface. At the same time, it is reusable due to the inherent properties of the components. More importantly, the CP-LAF-based TENG has strong adaptation and stability to a high-humidity environment. Its output voltage at 99 % relative humidity (RH) is 1.6 times that of 50 % RH owing to the triboelectrification involving a large number of water molecules and the increase in the contact area caused by material softening. Additionally, its electrical performance decreases very little after 5000 working cycles. Meantime, it suggests excellent application advantages in energy harvesting and self-powered sensing. This design strategy has the potential to solve the problem of the degradation of traditional triboelectric materials in high-humidity environments. The material provides a stimulating example for the design and preparation of green triboelectric materials that can withstand different humidity environments.