Sutapa Bhattacharya, a doctoral candidate in chemistry, will defend their dissertation titled “Exploring new Poly-Anion based Materials for LI-Ion Battery Cathodes.” Their advisor, Dr. Amitava Choudhury, is an associate professor in the chemistry department. The dissertation abstract is provided below.

The escalating global demand for sustainable energy storage solutions has driven intensive research into novel electrode materials. Polyanion-based cathode materials have emerged as promising candidates due to their structural stability, safety, and voltage tunability enabled by the inductive effect of polyanionic groups. This thesis explores the synthesis, crystal structure, and electrochemical performance of new polyanion-based cathode materials featuring vanadium, molybdenum, and iron within phosphate and selenite frameworks. Novel selenite-based materials, such as LiFe(SeO₃)₂ and Li₀.₂₅V₂O₃(SeO₃)₂, were synthesized and characterized, revealing stable electrochemical cycling associated with Fe³⁺/Fe⁴⁺ and V⁴⁺/V⁵⁺ transitions. Additionally, a systematic investigation was conducted on molybdenum phosphate compounds, including hydrated and anhydrous analogs of LiMo₂O₂(PO₄)₂(H₂PO₄)·xH₂O and Li₃Mo₂O₂(PO₄)₃. These frameworks exhibit open channels that support reversible lithium and sodium ion intercalation and demonstrate multielectron redox activity involving Mo⁴⁺/Mo⁶⁺ couples. These compounds exhibit structural integrity during Li-ion insertion enabling reversible Li intercalation. This research contributes to the broader understanding of how multivalent redox chemistry, polyanion selection, and structural design converge to create safe and high-capacity cathodes. The findings highlight the potential of polyanion frameworks to meet the performance and longevity requirements of next-generation lithium and sodium-ion batteries.