Scalable One-Pot Synthesis of Nanostructured P2-Type Na2/3Ni1/3Mn2/3O2 Cathode Material for High-Performance Na-Ion Batteries

Abstract

Sodium-ion batteries (SIBs) based on sodium transition metal oxides are considered as a viable alternative to lithium-ion batteries (LIBs) for grid-scale energy storage. This is because the critical elements used in these SIBs, such as sodium, manganese, and nickel, are abundantly available, and their supply chain does not pose any geopolitical risk like lithium and cobalt used in common LIB cathodes.1 Among sodium transition metal oxide cathodes, the P2-type Na2/3[Ni1/3Mn2/3]O2 (NNMO) is a promising material due to its high operating voltage (up to 4.5 V vs Na/Na+) and high capacity. When cycled between 2-4.5 V vs Na/Na+, it has a capacity of 173 mAh/g.2 This combination of high operating voltage and high capacity allows NNMO to outperform common LIBs in terms of energy density. Therefore, SIBs based on NNMO cathode are a scalable alternative to LIBs.Unfortunately, the current method used to produce NNMO through solid-state conversion is a time and energy-intensive process. It requires a temperature above 800 degrees Celsius and takes at least 12 hours to make a single batch of NNMO. Moreover, NNMO formed using this method has large particle sizes of a few micrometers. In my presentation, I will introduce a new and highly scalable method for synthesizing NNMO. This method can create NNMO in less than 20 minutes, which is much faster than the usual 12+ hours required by existing methods. Additionally, our protocol produces Nano-NNMO particles with size in the sub-200 nm. Nanoscale NNMO is crucial because it enhances the electrochemical performance of the materials, which I will also discuss. Key words: Sodium-ion batteries, Na2/3[Ni1/3Mn2/3]O2, high capacity, nanoparticles, rapid synthesis. References (1) Wang, C.; Liu, L.; Zhao, S.; Liu, Y.; Yang, Y.; Yu, H.; Lee, S.; Lee, G.-H.; Kang, Y.-M.; Liu, R.; et al. Tuning local chemistry of P2 layered-oxide cathode for high energy and long cycles of sodium-ion battery. Nature Communications 2021, 12 (1), 2256. DOI: 10.1038/s41467-021-22523-3.(2) Zhang, J.; Wang, W.; Wang, W.; Wang, S.; Li, B. Comprehensive Review of P2-Type Na2/3Ni1/3Mn2/3O2, a Potential Cathode for Practical Application of Na-Ion Batteries. ACS Applied Materials & Interfaces 2019, 11 (25), 22051-22066. DOI: 10.1021/acsami.9b03937.