title: Vacancy-driven anisotropic defect distribution in the battery-cathode material LiFePO4.
abstract: Li-ion mobility in LiFePO(4), a key property for energy applications, is impeded by Fe antisite defects (Fe(Li)) that form in select b-axis channels. Here we combine first-principles calculations, statistical mechanics, and scanning transmission electron microscopy to identify the origin of the effect: Li vacancies (V(Li)) are confined in one-dimensional b-axis channels, shuttling between neighboring Fe(Li). Segregation in select channels results in shorter Fe(Li)-Fe(Li) spans, whereby the energy is lowered by the V(Li)'s spending more time bound to end-point Fe(Li)'s. V(Li)-Fe(Li)-V(Li) complexes also form, accounting for observed electron energy loss spectroscopy features.
authors.affiliation: Department of Physics Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
authors.forename: Jaekwang
authors.initials: J
authors.lastname: Lee
authors.forename: Wu
authors.initials: W
authors.lastname: Zhou
authors.forename: Juan C
authors.initials: JC
authors.lastname: Idrobo
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Pennycook
authors.forename: Sokrates T
authors.initials: ST
authors.lastname: Pantelides