Elemental Modulation Inducing Defect Engineering to Enhance Electrochemical Capacitance and Rectification Performance of High-Entropy Oxides

Electrochemical capacitor diodes, integrating energy storage and ion rectification, hold great promise for practical applications. However, limitations in rectification ratio and specific capacitance hinder their widespread use. Here, high-entropy oxides were employed as electrode materials, with conductivity significantly enhanced via defect engineering and lattice optimization. Abundant oxygen vacancies increased active sites and accelerated surface reaction kinetics. Consequently, the (CrMnFeCoNiLi)₃O₄ electrode achieved an excellent specific capacitance of 272.04 F g^-1 and an energy density of 182.87 W h kg^-1, alongside favorable rectification performance (RRI = 6.5, RRII = 0.95). After 1000 cycles, the rectification ratio remained stable (RRI at 5.5, RRII at 0.95). Constant voltage tests further confirmed its suitability for electronic circuits. This study underscores the potential of defect-engineered high-entropy oxides in advancing high-performance energy storage and conversion devices.