Entropy engineering strategy boosting high-entropy spinel oxide electrode with impressive capacitance and energy density

Abstract

Spinel oxides are promising supercapacitor electrode materials due to their abundant active sites and tunable composition, yet their low conductivity limits energy density. This study employs entropy engineering to design a high-entropy spinel oxide, (Co_0.2Ni_0.2Cr_0.2Mn_0.2Cu_0.2)Fe₂O₄, by incorporating equiatomic metal dopants at the A site. Structural and chemical analyses confirm the successful synthesis of a single-phase high-entropy spinel. The material demonstrates exceptional electrochemical performance in 1 M KOH, achieving a specific capacitance of 1489 F g ¹ at 1 A g⁻¹, surpassing most reported high-entropy oxides. In an asymmetric supercapacitor with activated carbon (AC) as the negative electrode, it delivers a high energy density of 31.875 W h kg⁻¹ at 1074.8 W kg⁻¹. Remarkably, after 5000 cycles at 10 A g⁻¹, the material retains ∼60% of its initial capacitance with ∼90% coulombic efficiency. This work highlights a viable strategy for developing high-entropy electrode materials with significant application potential.