A series of high-entropy perovskite oxides (HEPOs) La(CoCrFeMnNiAl_x)_1/(5+x)O_3−δ (x = 0.4, 0.5, 0.6, and 0.7) have been synthesized by coprecipitation method combined with calcination process and explored as electrodes for supercapacitors. The crystal structure, microstructure, and elemental composition of HEPOs were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS) in detail. The electrochemical properties of HEPOs as supercapacitor electrodes were elucidated. The specific capacitances of HEPOs (x = 0.4, 0.5, 0.6, and 0.7) are 281.84, 353.65, 325.60, and 259.30 F/g at the current density of 1 A/g, respectively. After 2000 cycles, the specific capacitances of HEPOs (x = 0.4, 0.5, 0.6, and 0.7) remain 85.01%, 88.61%, 86.37%, and 91.25%, respectively. Such outstanding electrochemical properties can be attributed to the entropy-stabilized structure caused by mixed six cations in B-site and the Al³⁺-doping suppressing active ion aggregation during charge—discharge process. This research highlights the potential of HEPOs as electrodes for supercapacitors.

Environmental barrier coatings (EBCs) with excellent chemical resistance and good high-temperature stability are of great significance for their applications in next-generation turbine engines. In this work, a new type of high-entropy fluorite-structured oxide (Ce_0.2Hf_0.2Y_0.2Pr_0.2Gd_0.2)O_2−δ (HEFO-1) with different Ti⁴⁺ contents were successfully synthesized. Minor addition of Ti⁴⁺ could be dissolved into a high-entropy lattice to maintain the structure stable, effectively reducing the phase formation temperature and promoting the shrinkage of bulk samples. Heat treatment experiments showed that all the samples remained a single phase after annealing at 1200–1600 °C for 6 h. In addition, high-entropy (Ce_0.2Hf_0.2Y_0.2Pr_0.2Gd_0.2Ti_0.2x)O_2−δ demonstrated great resistance to calcium—magnesium—alumina—silicate (CMAS) thermochemical corrosion. When the content of Ti was increased to x = 0.5, the average thickness of the reaction layer was about 10.5 after being corroded at 1300 °C for 10 h. This study reveals that high-entropy (Ce_0.2Hf_0.2Y_0.2Pr_0.2Gd_0.2Ti_0.2x)O_2−δ is expected to be a candidate for the next-generation EBC materials with graceful resistance to CMAS corrosion.