A high-spin Mn-tailored sodium hexacyanoferrate electronic structure enables efficient Mg

Sodium hexacyanoferrate (NaFeHCF) is a promising cathode material for aqueous magnesium-ion batteries (AMBs) but suffers from limited active site utilization. Here, high-spin Mn is incorporated into the Fe sites of NaFeHCF to modulate its electronic structure, affording NaFe0.8Mn0.2HCF. The high-spin Mn efficiently optimizes the electronic structure of NaFeHCF and enhances its storage capacity for Mg2+. This work provides insights into the rational design of high-performance electrode materials for AMBs.