Enhancing supercapacitor performance with rapid response kinetics: CoMn2O4/Mn3O4/MnAl2O4(OV) spinels oxygen vacancies heterostructures for self-supporting integrated independent electrodes

In this research, a three-phase heterostructured mixture of CoMn₂O₄/Mn₃O₄/MnAl₂O₄(O_V) with a nanosheet spinel structure featuring oxygen vacancy defects was successfully synthesized using a dual-reaction strategy by dealloying combined with electrochemical deposition. The incomplete atomic matching in heterogeneous structures creates polarized electric fields at the interfaces. The electric field force generated by these polarized electric fields serves as an intrinsic driving force, accelerating ion diffusion and effectively facilitating the rapid transport of ions. The material reached a high area-specific capacitance of 17,700.32 mF/cm² at a current density of 2 mA/cm² and maintained 92.32 % of its capacitance after 5000 cycles at a current density of 6 mA/cm². Finally, an asymmetric supercapacitor was assembled with CoMn₂O₄/Mn₃O₄/MnAl₂O₄(O_V) as the positive electrode and reduced graphene oxide (rGO) as the negative electrode in 1.0 mol/L KOH electrolyte, yielding an energy density of 81.56 Wh/cm² and a power density of 639.93 W/cm³ . Impressively, at a power density of 3968.68 W/cm³ , it achieves an energy density of 45.40 Wh/cm². Furthermore, DFT simulations demonstrated that the synergistic effect of oxygen vacancy defects and heterostructures effectively adjusts the surface charge distribution and coordination environment, narrows the energy bandwidth, and significantly enhances the electrical conductivity of the material, thus dramatically accelerating the rate of electrochemical reactions.