Awarded Publication on Synthesis of Cathode Materials
Due to its importance for research on battery materials, the journal Chemistry of Materials recognized the publication “Monitoring the Formation of Nickel-Poor and Nickel-Rich Oxide Cathode Materials for Lithium-Ion Batteries with Synchrotron Radiation” as a Highlight in 2023. The paper, led by MEET PhD student Bixian Ying, decodes the reactions during the synthesis of nickel-rich and nickel-poor layered oxides.
Synthesis of High-performance Cathode Materials
Layered transition metal oxides, especially nickel-manganese-cobalt oxide cathodes (NMC), are the most common and versatile active materials for lithium-ion batteries. In their study, the scientists investigated both nickel-rich and nickel-poor NMC derived from hydroxide precursors by solid-state calcination. During this process, precursors mixed with a lithium source are subjected to heating under an oxygen or air flow to achieve the final material. Simultaneously, the flows serve to remove any residual evaporations. “We analyzed the parameters for an effective calcination to produce high-performance materials,” explains Bixian Ying, PhD student at MEET Battery Research Center at the University of Münster. The focus was on the steps of preannealing and holding at high temperatures, which are carried out during calcination. The team also investigated whether air or pure oxygen in the atmosphere influences the process.
“The preannealing step is particularly significant,” emphasizes Ying. “It allows the nickel to oxidize completely.” This reaction in turn determines the performance of the materials and therefore of the battery cells. In combination with holding at high-temperatures, preannealing favors an ordered structure of Ni-rich NMC. This improves the stability and lifetime of the battery cells. The calcination process also benefits from a pure oxygen atmosphere. “By further deciphering the influence of each step and thus gaining a deeper understanding of the processes, we were able to determine the parameters for effective calcination of raw materials,” says Ying.
Publication is Part of the Highlight Issue of Chemistry of Materials
Chemistry of Materials has now republished the entire study in its first issue in 2024. To mark the 35th anniversary of the journal, it includes highlights from 2023 that have significantly advanced battery research. Authors of the study are Bixian Ying, Zhenjie Teng, Vassilios Siozios, Prof. Dr. Martin Winter and Dr. Karin Kleiner (MEET Battery Research Center), Jack R. Fitzpatrick (Imperial College London), Tianxiang Chen and Tsz Woon Benedict Lo (Hong Kong Polytechnic University), Claire A. Murray, Sarah Day and Chiu C. Tang (Diamond Light Source, Oxfordshire), Helen E. A. Brand (The Australian Synchrotron), Robert S. Weatherup (University of Oxford) and Dr. Michael Merz, Peter Nagel and Dr. Stefan Schuppler (Karlsruhe Institute of Technology).