RESEARCH ARTICLE

Cryo-synthesized Prussian blue analogues as advanced cathode materials for potassium-ion batteries

¹ School of Physics and Electronics, Hunan University, Changsha 410082, China
² Greater Bay Area Institute for Innovation, Hunan University, Guangzhou 511300, China
³ College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
⁴ Department of Physics and Astronomy, Clemson Nanomaterials Institute, Clemson University, Clemson, SC 29634, USA
⁵ State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, China

^* Corresponding authors (emails: ctgao@hnu.edu.cn (Caitian Gao); luba2012@hnu.edu.cn (Bingan Lu))

Received: 9 June 2025
Revised: 24 June 2025
Accepted: 24 June 2025

Abstract

Prussian blue analogues (PBAs) are increasingly recognized as promising cathode materials for potassium-ion batteries (PIBs) owing to their low cost, distinctive open structure, and high theoretical capacity. However, PBAs still face challenges related to low crystallinity and elevated crystal water content, adversely affecting their performance as cathodes. This study proposes a straightforward low-temperature synthesis method for PBAs termed cryo-synthesized PBAs. The nucleation and growth processes were effectively slowed down by precisely controlling the synthesis temperature. This approach successfully yields PBAs with enhanced crystallinity and uniform particle size. The PBA electrode utilized as the cathode in PIBs demonstrates remarkable long-term cycling stability over 10,000 cycles at a current density of 2000 mA g⁻¹. We believe these findings will promote the widespread adoption of PBAs in aqueous PIBs, paving the way for large-scale, cost-effective applications.