Investigation of NaxFePO4 systems prepared by a modified Pechini sol-gel method as possible cathode materials for high voltage Na-ion batteries
Year: 2026
Type: preprint
Abstract: An uncomplicated modification of a Pechini assisted sol-gel process in water-polyol solutions is proposed for the synthesis of Na-Fe phosphate powders with different Na-ion content as cathode materials for sodium ion batteries (SIBs). Depending on the pH-values, X-ray diffraction detected the formation of Na-poor olivine-like o-NaFePO4 orthorhombic phase and o-FePO4 nanocrystalline structure. The cyclic voltammetry of the SIBs shows reduction peaks at ~2.23 V (x = 1.0) and ~2.12 V (x = 1.2) vs. Na/Na+ for pH < 3, and between 2.8 V - ~3.0 V (x = 1.0) for pH = 5 respectively. For x = 1.2, several redox peaks observed for pH=5 are assigned to a single-phase reaction (at ~2.5 V vs. Na/Na+) and two-phase reactions (at 3.0–3.25 V). Redox peaks above 4.5 V are more likely associated with Fe3+/Fe4+ redox coupling. A good cyclability is observed for the cathodes synthesized at both the pH values even by charging the batteries to the upper cut-off 4.8 V. The Na-cathode materials prepared under milder conditions showed the highest specific capacity of 40 mAhg-1.
Source: ChemRxiv
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7221967593