Coupling between oxygen redox and cation migration explains unusual electrochemistry in lithium-rich layered oxides.

ABSTRACT: Lithium-rich layered transition metal oxide positive electrodes offer access to anion redox at high potentials, thereby promising high energy densities for lithium-ion batteries. However, anion redox is also associated with several unfavorable electrochemical properties, such as open-circuit voltage hysteresis. Here we reveal that in Li_1.17-x Ni_0.21Co_0.08Mn_0.54O₂, these properties arise from a strong coupling between anion redox and cation migration. We combine various X-ray spectroscopic, microscopic, and structural probes to show that partially reversible transition metal migration decreases the potential of the bulk oxygen redox couple by > 1 V, leading to a reordering in the anionic and cationic redox potentials during cycling. Fir

SUBMITTER: Gent WE 

PROVIDER: S-EPMC5727078 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature