Innovative electrolytes for high power devices

This PhD thesis addresses challenges in performance, safety, and sustainability of lithium-ion batteries. A novel AgNbO₃-based perovskite anode is explored for LIBs, sodium-ion batteries, and potassium-ion batteries. The material’s unique structure, featuring exsoluted silver and open tunnel frameworks, enables fast Li⁺ diffusion and multi-valent Nb⁵⁺/Nb³⁺ redox activity. In LIBs, in-situ XRD, EELS, and XPS revealed a phase transition-driven amorphization that enhances lithium storage capacity. The role of A-site vacancies and Ag nanoparticle alloying was further clarified, highlighting the perovskite’s suitability for energy storage. AgNbO₃ also demonstrates pseudocapacitive behavior in Na⁺ and K⁺ systems. Operando Raman and ex-situ XRD indicate a similar activation mechanism to Li⁺ but with distinct voltage plateaus. While Na⁺ storage combines intercalation and surface redox processes, K⁺ storage is dominated by capacitive surface reactions, enabling efficient high-rate performance. These findings position AgNbO₃ as a versatile anode for multiple ion chemistries. Parallel work focused on LIB electrolyte design. A new formulation (DT2F), based on DOL:TEG solvents and LiFSI salt, showed superior thermal stability, low flammability, and a robust SEI. Electrochemical testing across wide temperature and C-rate ranges demonstrated enhanced performance versus conventional LP30. XPS and SEM confirmed a thinner SEI rich in -F and -S species, indicating favorable LiFSI decomposition pathways. Additionally, a bio-derived additive, itaconic anhydride (ITC), was studied as a sustainable and bio-sourced alternative to vinylene carbonate. ITC promotes SEI formation on graphite in PC-based electrolytes and mitigates co-intercalation and exfoliation. In-situ Raman revealed staged lithiation, and XPS identified polymerization-driven SEI formation rich in C–O/COO⁻ species. These results highlight ITC’s promise as a green additive for next-generation LIBs.