Defect properties and solution energies of dopants in NASICON-type LiGe₂(PO₄)₃ solid electrolyte: a first-principles...

Area of Science:

• Materials Science
• Solid-state electrochemistry
• Computational materials science

Background:

• NASICON-type solid electrolytes offer safer and more stable electrochemical performance for solid-state batteries.
• Lithium Germanium Phosphate (LiGe2(PO4)3, LGP) is a promising NASICON-type material.
• Understanding intrinsic defects and dopant behavior is crucial for optimizing LGP performance.

Purpose of the Study:

• Investigate intrinsic defects in LGP.
• Evaluate the energetics of incorporating various trivalent and tetravalent dopants at the Ge4+ site.
• Identify dopants that can enhance lithium-ion conductivity and chemical stability.

Main Methods:

• Density Functional Theory (DFT)-based calculations.
• Analysis of formation energies for intrinsic defects (Frenkel, Schottky, anti-sites).
• Calculation of solution energies for dopant incorporation and analysis of Bader charges and density of states.

Main Results:

• Lithium Frenkel pair formation is the most energetically feasible intrinsic defect.
• Aluminum (Al3+) and Titanium (Ti4+) are the most favorable trivalent and tetravalent dopants, respectively.
• Doping with Al3+ and Ti4+ alters lattice parameters and impacts Li+ migration pathways. Alkali atom doping at Li+ sites is favorable, while alkali-earth doping is not.

Conclusions:

• DFT calculations provide insights into defect energetics and dopant incorporation in LGP.
• Al3+ and Ti4+ doping are promising strategies for improving LGP-based solid electrolytes.
• Further experimental validation is needed to confirm the predicted improvements in lithium-ion conductivity and stability.