High-valent manganese promotes percolating K-vacancy networks to boost bulk K+ conduction in K2−γMnxFe4−xO7−δ

Abstract

We have developed K_2−γMn_xFe_4−xO_7−δ solid-state electrolytes with enhanced potassium vacancy concentration by substituting Fe with high-valent Mn. The increased vacancies create additional migration sites and percolation pathways for K⁺ ions, thereby lowering the activation energy and enhancing the ionic diffusion coefficient. As a result, the intrinsic ionic conductivity of the Mn-doped electrolyte at x = 2.0 is three orders of magnitude higher than that of the undoped counterpart.