Evaluating lithium diffusion mechanisms in the complex spinel Li₂NiGe₃O₈.

Area of Science:

• Materials Science
• Solid-State Chemistry
• Electrochemistry

Background:

• Understanding lithium-ion diffusion is crucial for developing advanced energy storage materials.
• Complex spinel structures present unique challenges for ion transport.
• Li2NiGe3O8 is a complex spinel material with potential applications in batteries.

Purpose of the Study:

• To investigate the lithium-ion diffusion mechanisms in Li2NiGe3O8.
• To determine the activation energies and diffusion coefficients for Li+ ion hopping.
• To understand the effect of sintering on lithium diffusion in this material.

Main Methods:

• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy.
• Impedance spectroscopy.
• Muon spectroscopy.

Main Results:

• Partial occupancy of migratory interstitial 12d sites was observed at lower temperatures than previously reported.
• Bulk activation energies for Li+ ion hopping ranged from 0.43 ± 0.03 eV (powdered) to 0.53 ± 0.01 eV (sintered at 950 °C for 24 h).
• A lithium diffusion coefficient of 3.89 × 10-12 cm2 s-1 was determined at 300 K using muon spectroscopy.

Conclusions:

• Sintering at elevated temperatures leads to Li loss, increasing activation energy for Li+ ion hopping.
• The findings provide insights into the lithium diffusion pathways in Li2NiGe3O8.
• This research contributes to the understanding of ion transport in complex oxide materials for energy storage applications.