Exploring Hollandite-Type KyVxTi8–xO16 (0.25 ≤ x ≤ 2) as Electrode Materials in Potassium-Ion Batteries (KIBs)
Year: 2025
Type: article
Abstract: Hollandite-type oxides, K y V x Ti 8– x O 16, x = 0.25, 0.5, 0.75, 1, 1.25, 1.5, and 2, are synthesized via the citrate method and evaluated as potential electrode materials for potassium-ion batteries (KIBs). Neutron powder diffraction (NPD) confirms an undistorted I 4/ m structure, uniform K content (1.4 ≤ y ≤ 1.6), and high potassium isotropic displacement parameter (B iso ). This decreases significantly for x ≥ 1, correlating with tunnel narrowing and vanadium’s stronger polarization. Transmission electron microscopy (TEM) techniques, including selected area electron diffraction (SAED), annular bright field (ABF), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) identify superstructure reflections assigned to potassium/vacancy short-range order along the c axis with disorder between tunnels. Magnetic studies reveal paramagnetic behavior down to 2 K, with antiferromagnetic interactions at low temperature except for x = 0.25 composition, which exhibits ferromagnetic interactions. The experimental magnetic moment suggests a low Ti 3+ content, with notable deviations at x = 1.25. The electrochemical performance is assessed via galvanostatic cycling using 2.5 M potassium bis(fluorosulfonyl)imide (KFSI) in triethyl phosphate (TEP) as electrolyte. At a rate of C/10, 2 K + are reversibly de/inserted per formula unit, comparable to K 0.17 TiO 2 . At C/5, K 1.5 V 0.75 Ti 7.25 O 16 demonstrates a reversible de/insertion of 1 K + /f.u., highlighting its potential for rechargeable KIBs.
Source: Inorganic Chemistry
Institutions: Universidad Complutense de Madrid, Institut Laue-Langevin
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
OpenAlex ID: W4409664259