Investigations on the properties of Li3xLa2/3-xTiO3 based all-solid-state supercapacitor: relationships between the capacitance, ionic conductivity, and temperature

Abstract All-solid-state ionic supercapacitors based ceramic oxides exhibit better characteristics than the conventional liquid-electrolyte supercapacitors in terms of high safety and broad working potential. However, there are rare reports referring to the working mechanism as well as factors impacting the capacities of these solid- state supercapacitors. In this work, Li3xLa2/3-x□1/3-2xTiO3 (LLTO, □ represents vacancy) materials with different lithium contents (nominal 3x = 0.33∼0.42) are synthesized and fabricated into solid-state supercapacitors, to study the capacity. Results exhibit that the Li0.33La0.56TiO3 can release the highest capacitance of 0.28 m F⋅ g-1 among the samples with superior cycling performance under a potential range of 2 V at 300 K, based on an Au∣LLTO∣Au cell configuration. The possible factors to affect the capacity include the lattice structures, ionic conductivity, and working temperature. This study may provide new insights into the design of more stable energy storage devices with better safety.