Unusual capacity boost in Li/TiF₃ cells enabled by a Li⁺/Na⁺ mixed solid electrolyte with high-voltage stability

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Titanium trifluoride (TiF3) is explored as a cathode material.
• Understanding charge storage mechanisms in novel battery materials is crucial.

Purpose of the Study:

• To investigate the electrochemical performance of TiF3 with a novel Li+/Na+ mixed electrolyte.
• To elucidate the charge storage mechanism in the TiF3-electrolyte system.

Main Methods:

• Electrochemical testing of TiF3 in a NaI-NaBH4-LiI mixed electrolyte.
• Analysis of redox processes to determine the storage mechanism.

Main Results:

• TiF3 demonstrated anomalously large capacity when paired with the Li+/Na+ mixed electrolyte.
• No Ti3+ redox activity was observed, indicating interfacial Li+ storage as the dominant mechanism.
• The mixed electrolyte exhibited superior high-voltage stability.

Conclusions:

• Interfacial Li+ storage is the primary mechanism responsible for the high capacity of TiF3.
• The Li+/Na+ mixed electrolyte offers enhanced stability, making TiF3 a promising candidate for solid-state batteries.