Highefficiency Prussian Blue Cathodes Advance Sodiumion Battery Performance

Prussian blue and its analogues are drawing attention as cathode materials for next-generation rechargeable metal-ion batteries, with an open-framework structure that can host a range of monovalent and multivalent ions. The materials are being evaluated for sodium, potassium, magnesium, calcium, zinc and aluminum systems, where stable frameworks and tunable redox sites are central requirements. Technical specifications for the SIB-NFCN series illustrate the performance profile now being targeted in sodium-ion battery development, including a specific capacity of 122 mAh/g.

Core material advantages

The appeal of Prussian blue materials rests on a stable skeleton, tunable redox-active sites and a relatively straightforward synthesis route. The open framework can accommodate metal ions of different sizes, creating transport channels suited to sodium-ion batteries and other emerging storage devices.

In testing, the SIB-NFCN series is specified at a specific capacity of up to 122 mAh/g, with first-cycle discharge capacity holding at about 120 mAh/g. Those figures place the material in the range sought for high-performance battery cathodes.

Specifications and electrochemical profile

The material’s chemical formula is Na2Fe2(CN)6. Its composition is listed as sodium at 40 ±1% and iron at 55 ±1%, with an operating voltage range of 2.1 to 3.8 V.

Physical characteristics include a tap density of 0.95 g/cm3, a specific surface area of 0.68 m2/g and a blue powder color. These parameters are relevant to slurry mixing, electrode coating and compaction during cell manufacturing.

Particle size options

Two particle-size distributions are specified to suit different electrode preparation methods and battery designs. The standard SIB-NFCN grade has a D10 of 4.2 um, a D50 of 19.9 um and a D90 of 47.6 um.

The SIB-NFCN-100 grade is milled more finely, with a D10 of 1.2 um, a D50 of 4.8 um and a D90 of 9.1 um. The smaller particles are intended for electrode designs that require higher surface area and faster kinetics, while the larger grade shows different behavior in slurry leveling and compaction density.

Handling and storage

Prussian blue materials are sensitive to moisture, which can affect the activity of redox sites and the cycling stability of finished cells. Storage in a vacuum dry box or an inert-gas-protected dry environment is required to limit exposure to air.

Electrode slurry preparation should follow a standard process to protect electrochemical performance. Solvent selection, mixing sequence and binder ratios are typically defined in the electrode preparation procedure used by cell makers.