High‐performance magnesium organic batteries using renewable biomolecule‐based cathode

Rechargeable magnesium batteries (RMBs) exhibit significant potential in large‐scale energy storage due to their features of high volumetric capacity, resistance to dendrite formation, and abundant magnesium resources. However, the high polarity of divalent Mg2+ ions results in sluggish diffusion kinetics in conventional inorganic cathode materials, adversely affecting reversible capacity and rate performance. Organic materials such as pyrene‐4,5,9,10‐tetrone (PTO) and 3,4,9,10‐perylenetetracarboxylic dianhydride (PTCDA), achieve rapid and reversible intercalation of magnesium ions through carbonyl enolization, but these materials are challenged by high cost, complex preparation, and poor environmental friendliness. In this study, we employ a carbonyl‐rich biomass‐based small molecule, emodin, as a cathode material for RMBs, achieving rapid diffusion kinetics and notable magnesium storage performance. Density functional theory (DFT) calculations indicate that two emodin molecules can form a stable structure capable of incorporating two magnesium ions when arranged with central inversion. This work demonstrates the feasibility of using biomass materials to prepare high‐performance cathodes for RMBs and provides a novel approach for the development of high‐performance organic cathode materials.