Changes in electronic structure upon lithium insertion into the A-site deficient perovskite type oxides (Li,La)TiO3

Area of Science:

• Materials Science
• Solid-State Chemistry
• Electrochemistry

Background:

• Perovskite oxides like (Li,La)TiO3 are promising materials for energy storage.
• Understanding electronic structure changes during lithium insertion is crucial for optimizing performance.

Purpose of the Study:

• To investigate the electronic structure variations in (Li,La)TiO3 during electrochemical lithium insertion.
• To elucidate the role of titanium, lanthanum, and oxide ions in the lithium insertion process.

Main Methods:

• X-ray absorption spectroscopy (XAS) at Ti K-edge, La L3-edge, and O K-edge.
• First-principles band structure calculations.

Main Results:

• Titanium ions reduced from Ti4+ to Ti3+ upon lithium insertion.
• Lanthanum ions (La3+) did not participate in the reduction reaction.
• Significant spectral changes at the O K-edge indicated altered electronic structure around oxide ions.
• First-principles calculations revealed electron transfer from inserted lithium to neighboring oxide and titanium ions.

Conclusions:

• The observed changes in O K-edge XAS are attributed to strong interactions between inserted lithium ions and oxide ions.
• Electron transfer from lithium to oxide and titanium ions helps neutralize local electrostatic interactions within the perovskite structure.