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Abstract Intermittent renewable energy sources can mitigate climate change, but they require high-performance, reliable batteries. The widely used lithium-ion batteries contain Li, Co, and Ni, and the growing demand for these elements, together with their relatively limited sources, has raised concerns about their supply chain stability. Sodium-ion batteries have become an economical alternative. Sodium vanadium phosphate, Na3V2(PO4)3 (NVP), is a compelling candidate with high stability and ionic conductivity due to its polyanionic sodium superionic conductor (NASICON) structure. However, NVP suffers from poor electronic conductivity and requires hierarchical morphology to allow facile ion and electron transfer. Spray-drying has been used to achieve hierarchical secondary particle structures, but the foremost reported NVP syntheses rely on either flammable/toxic organic solvents or expensive nanocarbon additives. In this study, we spray-dry an aqueous suspension without using expensive carbon additives. The obtained NVP sodium-ion half cells showed very high reversible capacity (114.7 mAh g-1 at 0.2C), high rate capability (80.8% capacity retention at 30C), and stable cycling performance (96.7% capacity retention after 1,500 cycles at 10C). This superior performance demonstrates the great promise for NVP batteries as an alternative energy storage option to traditional lithium-ion batteries.
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This content will become publicly available on September 9, 2027
Ten-Minute Microwave Synthesis of Microscale Na3V2(PO4)2O2xF3-2x Cathodes for Sodium-Ion Batteries
Na3V2(PO4)2O2xF3-2x (0≤x≤1) (NVPOF) is a promising cathode material for sodium-ion batteries, but conventional synthesis methods often require prolonged processing to obtain phase-pure material. Here, we report a 10-min microwave-assisted solution method that directly produces phase-pure, microscale NVPOF particles with well-defined tetragonal/cuboid morphologies using either NH4VO3 or V2O5 as the vanadium precursor. By systematically varying precursor chemistry, reaction temperature, and precursor concentration, we show that particle size (0.2–5 µm), crystallinity, morphology, and product yield can be tuned. The limited solubility of the V2O5 precursor leads to delayed and heterogeneous vanadium release, resulting in a bimodal particle-size distribution and possibly subtle differences in local vanadium redox environments, reflected in slightly different electrochemical behaviors. The as-synthesized micro-sized materials exhibit moderate rate capability and stable cycling. In situ XRD heating reveals a limited thermal stability window of the NVPOF sample. Guided by this result, a quick one-hour low-temperature heat treatment combined with carbon coating increases the discharge capacity to 118 mAh g-1 at C/10 and delivers 90.4% capacity retention after 300 cycles at 1C. These findings identify precursor selection and microwave reaction conditions as effective parameters for tailoring NVPOF structure and performance and provide a rapid route to NVPOF cathodes for sodium-ion batteries.
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- Award ID(s):
- 2409203
- PAR ID:
- 10711873
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Journal of power sources
- ISSN:
- 1873-2755
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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