Enabling High Voltage Operation of Layered Sodium Cathodes By Interface Modification

Résumé fourni par la source

Sodium-ion batteries (SIBs) are emerging as a viable and cost-effective alternative to lithium-ion batteries, largely due to their similar intercalation chemistry and reliance on earth-abundant materials. Among various cathode options, Mn- and Fe-based layered oxides, such as P2-type Na x (Ni,Mn)O 2 and O3-type Na(Ni,Mn,Fe)O 2 , have attracted considerable interest for their promising balance of performance, sustainability, and scalability. However, these materials face challenges related to structural and interfacial stability, particularly under high voltage conditions (>4.0 V vs. Na), where issues like bulk structural degradation, surface instability, and rapid capacity fading become more pronounced. This presentation will highlight the key degradation mechanisms limiting the high-voltage performance of Mn- and Fe-based layered oxide cathodes and present our recent strategies to overcome these hurdles. Specifically, we will discuss the effectiveness of metal fluoride surface coatings in mitigating surface and bulk degradation by suppressing gas evolution, catalytic electrolyte decomposition, and transition metal dissolution. In addition, we will explore the role of electrolyte formulations in improving cycling stability. These insights contribute to a deeper understanding of interface stability and offer a pathway toward more robust and commercially viable SIB technologies.

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