Vanadium diselenide (VSe2) is a promising cathode material for Magnesium–Lithium hybrid batteries (MLHB), owing to its favorable electronic structure and layered framework. However, practical Mg2+ storage is hindered by narrow interlayer spacing, strong Mg2+ host Coulombic interactions, and structural degradation during repeated ion insertion. Here, we introduce a molecular interlayer engineering strategy based on ethylenediamine (EDA) intercalation to address these challenges. A combination of theoretical calculations and experimental investigations reveals that EDA modification simultaneously expands the interlayer spacing, modulates the electronic structure, and weakens the Coulombic interactions between the lattice and the guest ions, thereby facilitating Mg2+/Li+ diffusion and enhancing reaction kinetics. Moreover, the electron-rich –NH2 groups of EDA engage in reversible chelation with the guest ions, providing additional storage sites and enabling an inorganic–organic synergistic storage mechanism based on topological intercalation reactions. As a result, the optimized E(0.2)-VSe2 cathode exhibits a stable capacity of 82.5 mAh g–1 over 4500 cycles at 1000 mA g–1, with a remarkable capacity retention of 72.7%. This work underscores molecular interlayer engineering as an effective strategy for enhancing the performance of layered cathodes in multivalent rechargeable batteries.
Li et al. (Fri,) studied this question.