Preparation of Y-Doped La2Ti2O7 Flexible Self-Supporting Films and Their Application in High-Performance Flexible All-Solid-State Supercapacitor Devices.

Flexible all-solid-state supercapacitors have drawn more attention owing to the rapid growth of wearable electronic equipments. Herein, we have succeeded in synthesizing a series of Y-doped lanthanum titanate flexible self-supporting films (LSF-x, 0.1 ≤ x ≤ 0.5) and investigating the change of microstructures, morphological characteristics, and lattice structures of these films affected by different Y-doping contents. To further determine the optimum Y-doping content, we have explored the electrochemical properties of working electrodes prepared by LSF-x (0.1 ≤ x ≤ 0.5) samples as the main active material. As the LSF-0.2 electrode has the best areal capacitance of 1.3 F·cm-2 at 2 mA·cm-2, we use the LSF-0.2 electrodes and PVA-Na2SO4 gel to fabricate a flexible all-solid-state supercapacitor device. This device has a high areal capacitance of 255.9 mF·cm-2 at a current density of 2 mA·cm-2 with a high cell voltage of 2.1 V, while the corresponding energy density is 156.8 µWh·cm-2 with a power density of 2.1 mW·cm-2. Moreover, it also shows a long cycling life and outstanding flexibility. Therefore, the LSF-0.2 sample can be used as an excellent energy-storage material for a wearable electronic device.