Investigating microstructure evolution of Mg-ion battery cathodes with simultaneous heating and electrochemistry in-situ microscopy*

Barriers to lithium-ion battery development, such as the limited energy density of Li-ion batteries and the scarcity of Li, have led to great interest in exploring multi-valent ionic batteries containing earth-abundant intercalation elements, such as magnesium or calcium. Reversible intercalation of Mg²⁺ ions is a crucial part of constructing a stable battery, which, when combined with high capacity, charts a promising pathway towards high performance and future designs of Mg-ion batteries. High levels of reversible Mg²⁺ intercalation have been reported in α-V₂O₅ by cycling assembled cells at an elevated temperature of 110°C, the benefit of which is retained at room temperature. The ex-situ experiments demonstrate that α-V₂O₅ can intercalate at least one mole of Mg²⁺ reversibly at 110°C, as opposed to <0.6 moles at 25°C. The capacity of the α-V₂O₅ is increased 20-fold, matching the performance of Li-ion batteries. Structural changes accompany this increase in electrochemical performance; the morphology of the α-V₂O₅ powders drastically changes from platelets to delaminated layers, and spectroscopy of Mg content change echoes the electrochemistry.

Current research is ongoing to explore in-situ characterization combined with capabilities of simultaneous heating and electrochemical cycling. If realized in realistic Mg-battery research, this can open up more possibilities to deepen the understanding of structural evolution and chemical developments during the intercalation process. This poster presents preliminary results obtained during the benchmarking of the state-of-the-art instrumentation, as well as prospects for future experimentations.