Rechargeable Mg–Br2 Battery with Ultrafast Bromine Chemistry

A sustainable society necessitates the support of diversified energy storage systems. Magnesium metal batteries, known for the environmental friendliness, safety of dendrite-less, cost-effective, and high volumetric capacity of magnesium metal, exhibit promising prospects. However, the high charge density of the magnesium ion leads to sluggish ion diffusion in cathodes, posing challenges for developing magnesium metal battery systems with high power and high energy density. Here, inspired by the Hard-Soft-Acid-Base theory, we propose a soft-anion-induced bond weakening strategy to address the diffusion difficulty. The bulky and broadly electron-distributed succinimide ion (SN