Engineering cathode electrolyte interface for low co and co-free lithium ion batteries
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Authors
Mahajani , Varad
Issue Date
2025-08
Type
Electronic thesis
Thesis
Thesis
Language
en_US
Keywords
Materials engineering
Alternative Title
Abstract
The advancement of high-energy lithium-ion batteries and quest to lower cathode costs is critically limited by the interfacial instability of Ni-rich and high-voltage cathode materials under high cutoff voltages. This work addresses two key materials challenges - electrolytedriven surface degradation in Ni-rich layered oxides and in spinel-type cathodes - through targeted surface engineering strategies. Firstly, a magnetite (Fe₃O₄) nanoparticle coating was developed for NMC811 cathodes to suppress parasitic reactions and structural deterioration at high voltages (up to 4.6 V vs. Li/Li⁺). The iron-based coating acted as a chemically robust interface, mitigating electrolyte decomposition transition metal dissolution and surface oxygen loss, thereby enabling stable long-term cycling with enhanced energy density. Secondly, nearsurface oxygen vacancies were introduced on LiNi₀.₅Mn₁.₅O₄ (LNMO) cathodes via controlled ammonia solution treatment. This approach tailored the surface defect chemistry interfacial transport pathways. The resulting vacancy-rich surface not only improved Li⁺ diffusion kinetics but also imparted greater tolerance against electrolyte oxidation and Mn dissolution during operation above 4.6 V (vs Li/Li+). A suite of materials and electrochemical analysis has been carried out to reveal the improvements and substantiate proposed mechanisms. Together, these materials-centric strategies highlight the importance of interface design in overcoming intrinsic limitations of next-generation cathodes. This work provides a foundation for developing highvoltage, cobalt-free cathode systems with improved chemical stability and electrochemical performance.
Description
August2025
School of Engineering
School of Engineering
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY