Organic cathodes offer great promise for rechargeable magnesium batteries (RMBs) owing to their structural tunability and fast Mg 2+ transport, yet their dissolution in ether‐based electrolytes leads to rapid capacity fading and poor rate performance. Herein, we design a high‐performance sulfur‐containing heterocyclic quinone cathode, benzobnaphtho2′,3′:5,61,4dithiino2,3‐ithianthrene‐5,7,9,14,16,18‐hexone (BNDTH), coupled with a functional carbon‐coated separator composed of graphene oxide (GO) and carboxylated multi‐walled carbon nanotubes (MWCNTs−COOH) at an optimized 1:9 mass ratio. In this architecture, GO provides physical confinement to suppress BNDTH diffusion, while MWCNTs−COOH offer abundant chemical adsorption sites to immobilize soluble species. This synergistic confinement–adsorption mechanism effectively mitigates active‐material loss and promotes charge transfer. As a result, the Mg//BNDTH cell exhibits significantly improved rate capability, delivering cathode capacities rising from 153 to 261 mAh g −1 at 1 C and from 26 to 100 mAh g −1 at 10 C over 500 cycles, along with cell‐level power and energy densities of 4517 W kg −1 and 222 Wh kg −1 , respectively—surpassing most reported RMBs employing organic cathodes. This work presents a viable separator‐engineering strategy for achieving stable and high‐rate operation of soluble organic cathodes in RMBs.
Qi et al. (Thu,) studied this question.