Looking Beyond Lithium for Breakthroughs in Magnesium-Ion Batteries as Sustainable Solutions

The increasing demand for sustainable and cost-effective battery technologies in electric vehicles (EVs) has driven research into alternatives to lithium-ion (Li-ion) batteries. This study investigates magnesium-ion (Mg-ion) batteries as a potential solution, focusing on their energy density, cycle stability, safety, and scalability. The research employs a comprehensive methodology, combining electrochemical testing and simulation models, to analyse magnesium-based anodes, sulphur-based cathodes, and advanced electrolytes such as HMDS2Mg. Key findings reveal that Mg-ion batteries achieve a practical energy density of 500–1000 mAh/g, comparable to high-performance Li-ion systems. With sulphur–graphene cathodes, Mg-ion batteries demonstrated 92% capacity retention after 500 cycles, a 10% improvement over standard configurations. Ionic conductivity reached 1.2 × 10−2 S/cm using HMDS2Mg electrolytes, significantly reducing passivation layer growth to 5 nm after 100 cycles, outperforming Grignard-based systems by 30%. However, the research identified a 15% reduction in charge–discharge efficiency compared to Li-ion batteries due to slower ion diffusion kinetics. This study highlights the safety advantage of magnesium-ion batteries, which eliminate dendrite formation and reduce thermal runaway risks by 40%. These findings position Mg-ion batteries as a promising, sustainable alternative for EVs, emphasising the need for further optimisation in scalability and efficiency.