Anion‐Confined Interface Enabling Uniform Stripping of Magnesium Anode

The non‐uniform stripping behavior of magnesium (Mg) anodes severely limits their utilization ratio and areal capacity, presenting a critical barrier to the practical application of Mg‐based batteries. Herein, an anion‐confined interface on the Mg anode is introduced that facilitates uniform stripping by regulating the migration of interfacial anions. This strategy enables Mg anodes to achieve a record‐high areal capacity of 17.24 mAh·cm −2 with a utilization ratio of 90%. Consequently, an unprecedented ampere‐hour‐scale rechargeable Mg‐ion pouch cell is demonstrated. Furthermore, modified Mg‐air batteries exhibit stable operation with a high average energy density of 2300 Wh·kg −1 , reducing performance deviation from 16.3% to 4.4%. These findings provide mechanistic insights into ion migration control at the Mg interface and offer a robust pathway toward high‐performance Mg‐based batteries.