Solid state bridging of magnesium oxide rock salt with reduced graphene oxide through MgH2 for Li and Na ion rechargeable battery applications

A magnesium oxide rock salt anchored reduced graphene oxide (MgO–rGO) hybrid nanostructure was developed through a simple redox reaction between MgH 2 and graphene oxide. The process involves mechanical milling of a GO + 10 wt% MgH 2 composite followed by thermal treatment under nitrogen atmosphere. Structural analyses confirm the transformation of MgH 2 –GO into MgO-linked rGO with uniformly dispersed MgO. X-ray photoelectron spectroscopy depth profile analysis confirms the presence of MgO at both the surface and bulk regions of the MgO–rGO hybrid structure. This structure exhibits excellent electrochemical performance as an anode material for both lithium-ion and sodium-ion batteries, delivering specific capacities of 447 and 217 mAh g −1 , respectively, at 100 mA g −1 . Electrochemical impedance analysis reveals a lithium diffusion coefficient an order of magnitude higher than that of sodium (7.40× 10 −9 vs. 8.16 × 10 −10 cm 2 s −1 ), consistent with the lower charge transfer time constant and superior rate capability of Li-ion cells. Extended cycling (3000 cycles at 1 A g −1 ) indicates an earlier onset of intercalation-induced perturbation in the Li-ion battery relative to the Na-ion battery, which is corroborated by postmortem investigations. Overall, this work expands the functional scope of MgH 2 beyond hydrogen storage, highlighting its promise in designing durable, high-performance electrodes for next-generation sustainable energy devices.