Oxygen vacancies and ordering of d-levels control voltage suppression in oxide cathodes: the case of spinel LiNi0.5Mn1.5O4-δ

Journal Article · Wed Jun 19 00:00:00 EDT 2013 · Advanced Functional Materials, 23(44):5530-5535

DOI:https://doi.org/10.1002/adfm.201301205· OSTI ID:1132720

Sushko, Petr V.; Rosso, Kevin M.; Zhang, Jiguang; Liu, Jun; Sushko, Maria L.

Spinel Li-Mn rich oxides form one of the most promising classes of high voltage cathode materials for next generation Li-ion batteries for electric vehicle applications. Our simulations for spinel LiNi0.5Mn1.5O4 (LNMO) show that neutral oxygen vacancies promote formation of Ni-rich regions, which are negatively charged with respect to the lattice. This makes the electrons associated with these vacancies to localize on Mn3+ eg states of two types: shallow states in the Ni-rich regions and deep states in the Ni-poor regions. The positive electrostatic potential produced by the oxygen vacancies and the existence of the shallow and deep Mn3+ states result in appearance of the low-voltage region at high Li content and high-voltage region at low Li content. This is consistent with characteristic changes in the voltage capacity curves observed experimentally during electrochemical cycling. We propose that doping LNMO with judiciously selected cations can help to remedy voltage suppression effects. This approach may also be used to enhance the electrochemical stability of Li-Mn rich oxides, which tend to experience continuous voltage fade.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1132720
• Report Number(s): PNNL-SA-93845
• Journal Information: Advanced Functional Materials, 23(44):5530-5535, Journal Name: Advanced Functional Materials, 23(44):5530-5535
• Country of Publication: United States
• Language: English