PANI/PVDF-TrFE porous aerogel bulk piezoelectric and triboelectric hybrid nanogenerator based on in-situ doping and liquid nitrogen quenching

Limited by the inherent properties of being difficult to be polarized due to its high resistance, PVDF bulk material with high β-phase content is hard to obtain by conventional methods which are suitable for membrane material. Herein, a novel strategy is proposed for the mass production of high-performance β-PVDF-based piezoelectric and triboelectric hybrid nanogenerator (PTNG) employing large-scale PVDF films or bulks by using liquid nitrogen to induce a phase transition and in-situ doped conductive polyaniline (PANI). Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) with high piezoelectric coefficient, filled with PANI as a conductive material and sodium carboxymethyl cellulose (SCMC) for increasing porosity, is hot pressed to obtain a composite piezoelectric polymer for PTNG. The subsequent “quenching” process of the piezoelectric polymer allows its high content of β-phase, which in turn makes the PTNG exhibit excellent piezoelectric properties. The optimal output of the PTNG, with a β-phase content of up to 71%, reaches 246 V and 122 μA at the frequency of 30 Hz and pressure of 0.31 MPa, and the power density is calculated to be 6.69 W/m2. Moreover, the PTNG can directly light up 119 blue light-emitting diodes (LEDs) with a size of 3 mm in series. The excellent performance verifies the reliability and accuracy of the method, that is, the β-phase transformation of disordered amorphous PVDF occurs at low temperature and high-rate quenching, and PANI opens the channel for carriers to move charge in the bulk material. This innovative method presented here is a simple and efficient approach for preparation of bulks with high β-phase and low internal resistance, which undoubtedly provides a feasible direction for the industrialization of high-performance PENGs.