High energy storage performance of Sr-doped lanthanum titanate flexible self-supporting film for all-solid-state supercapacitor application

Abstract Since the previous research confirms the lanthanum titanate (LTO) flexible self-supporting film can be considered as excellent energy storage material, we intend to maximize the performance of LTO to provide higher energy density for practical application. In order to achieve this goal, the Sr element was a choice to substitute with La for increasing the amount of oxygen vacancies in this study, and mechanical flexibility of the film was also maximally preserved. For determining the most appropriate amount of Sr doping, a serious of Sr-doped LTO films marked as LTO- x (0.1 ≤  x  ≤ 0.5) were synthesized by electrospinning combined with calcination method. After analyzed by the XRD, SEM, TEM, XPS and electrochemical work station, the LTO-0.3 sample shows the best properties with a maximum capacitance of 1.8 F·cm −2 at 2 mA·cm −2 . As a result of that, we fabricated the flexible all-solid-state supercapacitor device with two LTO-0.3 electrodes and PVA-Na 2 SO 4 gel. This LTO-0.3//LTO-0.3 device exhibits excellent cycling stability, outstanding flexibility and high energy density of 209.4 μWh·cm −2 with the corresponding power density of 2.1 mW·cm −2 . Graphical Abstract