Evaluating lithium diffusion mechanisms in the complex spinel Li2NiGe3O8

Abstract

Lithium-ion diffusion mechanisms in the complex spinel Li₂NiGe₃O₈ have been investigated using solid-state NMR, impedance, and muon spectroscopies. Partial occupancy of migratory interstitial 12d sites is shown to occur at lower temperatures than previously reported. Bulk activation energies for Li⁺ ion hopping range from 0.43 ± 0.03 eV for powdered samples to 0.53 ± 0.01 eV for samples sintered at 950 °C for 24 h, due to the loss of Li during sintering at elevated temperatures. A lithium diffusion coefficient of 3.89 × 10⁻¹² cm² s⁻¹ was calculated from muon spectroscopy data for Li₂NiGe₃O₈ at 300 K.