A New Candidate in Polyanionic Compounds for a Potassium-Ion Battery Cathode: KTiOPO₄

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Potassium-ion batteries (PIBs) are emerging as a sustainable energy storage solution.
• Developing high-performance cathode materials is crucial for advancing PIB technology.

Purpose of the Study:

• Investigate KTiOPO4 (KTP) as a potential cathode material for PIBs.
• Evaluate the stability, electronic properties, and K+ ion dynamics in KTP.
• Determine the feasibility of KTP for high-voltage applications.

Main Methods:

• First-principles computations (PBE+U and HSE06 functionals).
• Ab initio molecular dynamics (AIMD) simulations at 300 K.
• Analysis of de-potassiation, diffusion barriers, and volume changes.

Main Results:

• KTP exhibits stable depotassiation with oxygen hole polaron formation, avoiding peroxide/superoxide species.
• Anionic oxygen redox contributes to high operating voltages (>4 V with PBE+U, >5 V with HSE06).
• Minimal volume compression (1.528%) upon full K removal and good thermal stability of TiOPO4 were observed.
• Low K+ diffusion barrier (0.29 eV) suggests excellent charge-discharge rates.

Conclusions:

• KTP demonstrates significant potential as a cathode material for potassium-ion batteries.
• Its favorable electronic properties, stability, and ion kinetics support its use in high-voltage PIBs.
• KTP offers a promising pathway for developing efficient and durable energy storage devices.