Unravelling Solid-State Redox Chemistry in Li1.3Nb0.3Mn0.4O2 Single-Crystal Cathode Material
Wang Hay Kan, Dongchang Chen, Joseph K. Papp, Alpesh Khushalchand Shukla, Ashfia Huq, Craig Brown, Bryan D. McCloskey, Guoying Chen
Recent reports on high capacities delivered by Li-excess transition-metal oxide cathodes have triggered intense interest in utilizing reversible oxygen redox for high-energy battery applications. In order to control oxygen electrochemical activities, fundamental understanding of redox chemistry is essential, yet so far proven challenging. In the present study, micron-sized Li1.3Nb0.3Mn0.4Od2^ single crystals were synthesized for the first time and used as a platform to understand the charge compensation mechanism during Li extraction and insertion. We explicitly demonstrate that the oxidation of O2- to On- (02 loss from the lattice dominates at 4.5 V and 4.7 V, respectively. While both processes occur in the first cycle, only the redox of O2-/On- participates in the following cycles. The lattice anion redox process triggers irreversible changes in Mn redox, which likely causes the voltage and capacity fade observed on this oxide. Two drastically different redox activity regions, a single-phase behavior involving only Mn3+/4+ and a two-phase behavior involving O2-/Oun- (0less than or equal}n 2), were found in LixNb0.3Mn0.4O2 (0
, Chen, D.
, Papp, J.
, Shukla, A.
, Huq, A.
, Brown, C.
, McCloskey, B.
and Chen, G.
Unravelling Solid-State Redox Chemistry in Li<sub>1.3</sub>Nb<sub>0.3</sub>Mn<sub>0.4</sub>O<sub>2</sub> Single-Crystal Cathode Material, Chemistry of Materials, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=925055
(Accessed October 17, 2021)