Ultralight PPy@PVA/BC/MXene composite aerogels for high-performance supercapacitor eltrodes and pressure sensors

Directional freezing is an efficient approach to design anisotropic materials with surface void and well-defined aligned channels along the freezing direction for charge transmission and ion diffusion. Herein, poly(vinyl alcohol) (PVA)/bacterial cellulose (BC)/MXene (PBM) composite aerogels are prepared via directional freezing. The aligned porous architecture of PBM not only enables uniform loading and high accessibility of PPy through the aerogel network, but also ensures efficient penetration and fast transport of electrolytes. The as-prepared PPy@PVA/BC/MXene (PPy@PBM) aerogel based supercapacitors show a high areal specific capacitance of 3948 mF cm-2 at 0.47 mA cm-2, a desirable energy density 178 mu Wh cm-2 at a power density of 951 mu W cm-2 and excellent cycling stability (120% capacitance retention after 10,000 cycles). In addition, the PPy@PBM aerogels demonstrate high sensitivity (313.2 kPa- 1 in 200 to 3000 Pa pressure range), ultralow detection limit (<1 Pa) and fast response (79 ms) as pressure sensors. This study proposes an efficient approach to prepare porous composite aerogels for supercapacitor electrodes and pressure sensors.