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arXiv · 2310.01295

A review and outlook on anionic and cationic redox in Ni-, Li- and Mn-rich layered oxides LiMeO2 (Me = Li, Ni, Co, Mn)

Bixian Ying·Zhenjie Teng·Sarah Day·Dan Porter·Martin Winter·Adrian Jonas·Katja Frenzel·Lena Mathies·Burkhard Beckhoff·Peter Nagel·Stefan Schuppler·Michael Merz·Felix Pfeiffer·Matthias Weiling·Masoud Baghernejad·Karin Kleiner
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Abstract

The present work reviews the charge compensation in Ni based layered oxides (LiNi1-xMexO2 with x <= 0.2, Me = Co, Mn, space group R-3m) relating performance parameters to changes in the electronic and crystallographic structure of the cathode materials. Upon charge and discharge two fundamentally different redox mechanisms are observed: At low and medium states of charge (SOCs) charge compensation takes mainly place at oxygen sites while electron density is shifted from the oxygen lattice to nickel (formation of sigma bonds). At high SOCs the shift of electron density from the transition metals to oxygen (formation of pi bonds) enables an additional redox process but also oxygen release from the transition metal host structure and subsequent detrimental reactions. Depending on the Ni:Co:Mn content, both processes lead to characteristic features in the voltage profile of the cathode materials and performance parameters like the capacity, the cycling stability and the open cell voltage become a function of the composition.

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Bixian Ying, Zhenjie Teng, Sarah Day, Dan Porter, Martin Winter, Adrian Jonas, Katja Frenzel, Lena Mathies, Burkhard Beckhoff, Peter Nagel, Stefan Schuppler, Michael Merz, Felix Pfeiffer, Matthias Weiling, Masoud Baghernejad, Karin Kleiner. 2023-10-02. A review and outlook on anionic and cationic redox in Ni-, Li- and Mn-rich layered oxides LiMeO2 (Me = Li, Ni, Co, Mn). https://arxiv.org/abs/2310.01295

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