Fabrication of polyethyleneimine-paper composites with improved tribopositivity for triboelectric nanogenerators

Significant progress has been made in the fabrication of paper-based triboelectric nanogenerators (TENGs) through the increase of the electron-donating ability of cellulose paper. However, challenges still exist in the mass production of cellulose-based tribopositive materials with high output performance. Herein, a facile method was developed to improve the tribopositive performance of cellulose paper by simply loading branched polyethyleneimine (PEI). By changing the loading weight of PEI, PEI-paper composites with different structures and mechanical properties were prepared. The PEI-paper composites show drastically improved triboelectric output performance with an increasing loading weight of PEI because of their sharply increased relative permittivity. By loading 7.5 mg/cm2 PEI to form a network structure and loading 22.5 mg/cm2 PEI to form a hydrogel-like structure, the triboelectric output performances of the formed PEI-paper composite-based TENG are increased by approximately 4 and 6 times, respectively, and their power densities are increased by approximately 7.5 and 16 times, respectively. The PEI-paper composite-based TENG can serve as a self-powered pressure sensor to sense different external stimuli under different working modes and construct self-powered electric skin. Meanwhile, the occurrence of PEI also confers PEI-paper composites with water resistance, antibacterial activity, and flame retardation, yet the disposability of the paper remains. This work provides a simple method for improving the triboelectric performance of cellulose paper.