Donggun Eum’s Post

Delighted to share the publication of our latest paper in Nature Communications! (https://lnkd.in/gfz6mV67) Lithium-rich layered oxides represent a class of materials offering high-energy density surpassing current Ni-rich NMC layered cathodes. However, their distinctive oxygen redox activity triggers irreversible dynamic structural changes, impeding their commercial viability as near next-generation cathode materials. In this regard, I previously reported O2-type lithium-rich layered cathodes with different oxygen stacking sequences, revealing their potential for facilitating reversible structural changes even during oxygen redox participation. (https://lnkd.in/gPw_PNPK and https://lnkd.in/gZmWrucg) By expanding these findings, our latest publication investigates the compositional space to unveil hidden chemistry in this novel material class. Here are four key findings: 1. Lithium content, determining the extent of oxygen redox, is controlled to understand how the amount of oxygen redox can be stabilized in the new O2-type lithium-rich cathodes. 2. Excessive lattice oxygen redox triggers abrupt lattice collapse and disordered states, facilitating premature crack generation at the particle levels. Building on this, we established a trilateral relationship among anionic redox utilization, bulk chemo-mechanical degradation, and electrochemical fading. 3. The origin of voltage and capacity fading in lithium-rich cathodes is decoupled. Through systematic control of structural reversibility via O2-type stackings, we clearly demonstrated that capacity fading is not directly linked to (ir)reversible structure changes, which are associated with voltage decay. Instead, the formation of electrochemically inactive phases due to extensive lattice breathing, whether reversible or not, is experimentally observed to be more closely associated with capacity fade. 4. Redox balance between cationic (Nickel in this paper) and anionic redox is a determinant to lead to microcracking within single particles. With this understanding, we proposed long-lasting lithium-rich layered cathodes by tuning compositions of Lithium and Nickel in the structures. Ho-Young Jang and I worked together on this project, and I would like to express my gratitude to Professor Kisuk Kang for his supervision, as well as to all my collaborators for their valuable contributions.