Our Technology | Prussian White Cathode Material for Sodium-Ion Batteries
The global battery market is shifting toward a multi-chemistry future. As renewable power, grid stabilisation, and light mobility scale, the market needs battery technologies built on abundant, cost-aligned, and geographically resilient materials. Sodium-ion batteries (SIBs) answer this need. Sodium is over a thousand times more abundant in the Earth’s crust than lithium, costs a fraction as much per kilogram, and is evenly distributed across geographies, eliminating the supply concentration risks that constrain lithium.
Prussian White as Cathode Material for SIBs
Prussian White is one of the most promising cathode active materials for sodium-ion batteries. It is the fully reduced and sodiated form of Prussian Blue, represented as Na₂Fe[Fe(CN)₆], and functions as the positive electrode material in a sodium-ion cell.
How Prussian white works
In a sodium-ion cell, Prussian White acts as a host structure for sodium ions. Its ordered, open rhombohedral framework stays stable through rapid charge–discharge cycling, while sodium ions move reversibly in and out. Each movement is coupled with a reversible change in the oxidation state of the framework’s iron atoms.
On discharge-
1
Sodium ions migrate from the electrolyte into the cathode; electrons arrive through the external circuit
2
Iron accepts the electrons and shifts from Fe³⁺ to Fe²⁺
3
The lattice fills with sodium ions - Prussian Blue transforms into Prussian White
On charge-
1
Sodium ions are extracted and move toward the anode; electrons are released back into the circuit
2
Iron reverts from Fe²⁺ to Fe³⁺
3
The cathode returns toward the Prussian Blue state
Because iron readily switches between these two oxidation states, the Fe²⁺/Fe³⁺ redox process repeats reliably over thousands of cycles, enabling the material to store and release energy efficiently.
Why Prussian White?
| Chemical / Structural Property | Relevance in Battery Application |
|---|---|
| Open framework | Allows fast ionic conductivity. |
| Non-oxygen framework | Enhances safety by lowering thermal runaway risk. |
| Structural stability of the framework | Ensures minimal volume change during cycling, maintaining capacity and extending battery life. |
| Iron, Nitrogen and Sodium-based composition | Low toxicity and sustainable material choice. |
| Compatibility with Aluminium current collector | Reduces overall cost and simplifies fabrication process. |
| Low-cost materials (Na, N, Fe) used in composition | High scalability and simple synthesis. |
Our Prussian White Cathode Material
Macsen has developed a proprietary synthesis route that addresses moisture, oxygen, and scale constraints that have generally limited Prussian White to laboratory-scale production. The single-step, single-vessel process is carried out under controlled inert atmosphere, consolidating synthesis, reduction, and crystallisation into one operation that minimises air exposure and is built for industrial scale from the outset. A provisional patent covering the process was filed in July 2025, patent no. – IN20241196121A.
The result is a highly crystalline, fully sodiated, and air-stable Prussian White. Our Prussian White material is characterized by low moisture content and a rhombohedral crystal structure, and has the following electrochemical properties-
- Specific capacity: >150 mAh/g over 1000 cycles (on par with LFP)
- Coulombic efficiency: ~99.9%
- Cycling stability: Excellent reversibility across cycling, supported by Prussian White’s robust open-framework structure that undergoes minimal degradation over time.
- Air stability: Higher stability, which enables easy handling in commercial-scale production
Macsen’s Prussian White – Cell Performance
(Charge-Discharge Curve – Stable Electrochemical Performance over 1000 cycles with 90% capacity retention)
(Charge-Discharge Curve – Cell working at 90% capacity retention over 1000 cycles and 99.9% coloumbic efficiency)
(Charge-Discharge Curve – Cell working at 90% capacity retention over 1000 cycles and 99.9% coloumbic efficiency)
Sodium Ion Cell Technology
Macsen Energy’s work extends beyond cathode material development. The team is developing sodium-ion cell technology centred around Prussian White as the cathode material, with parallel efforts focused on compatible anode materials, electrolyte systems, and cell engineering. The team is also working on scalable manufacturing and fabrication methods that do not rely on imported equipments, thereby enabling a more localized and cost-effective sodium-ion battery ecosystem.
The primary development pathway pairs Prussian White cathode material with hard carbon anode material, a widely studied sodium-ion configuration. We are also evaluating additional strategies for full-cell development, including alternative anode materials and anode-free configurations.
Our Battery R&D Lab
Macsen Energy operates an integrated battery R&D setup that supports the complete early-stage development cycle: material synthesis, inert handling, electrode preparation, cell fabrication, and electrochemical testing.
Laboratory capabilities –
- Chemical synthesis fume hoods
- Coating Machine for electrode coating
- Roll Press Machine for electrode compaction
- Vacuum Mixer for slurry preparation
- Coin Cell Crimper for half-cell assembly
- Electrode Punching Machine
- Argon-filled glove box for inert-atmosphere handling
- Muffle Furnace for high-temperature processes
- Ball Mill for material grinding
- Coin and pouch cell fabrication stations
- Vacuum dryers
- Electrochemical testing systems, including a Galvanostatic cycler and potentiostats
- Advanced analytical instruments including HPLC, LC-MS/MS with PDA, GC-MS/MS with Headspace, UV-Vis Spectrophotometer, ICP-OES, ICP-MS, and FTIR
Applications of our Prussian White Technology
Macsen Energy’s Prussian White cathode material is being engineered for a range of low-voltage sodium-ion battery applications, including:
- Grid and stationary energy storage - Battery energy storage systems (BESS) for grid stabilisation, solar energy storage, distributed stationary storage and renewable energy applications.
- Electric mobility - 2-wheelers, 3-wheelers, auto-rickshaws, city buses, and entry-level EVs, where sodium-ion's cost and safety profile align with India's volume mobility segments.
- Industrial and backup power - Rural microgrids, telecom and data centre backup, and industrial vehicles such as forklifts and warehouse loaders. Sodium-ion cells offer a structural safety advantage here; unlike lithium-ion, they can be transported in a fully discharged state.
- Household and commercial backup- Inverter systems, home backup systems, small commercial power backup, and Residential solar storage, where reliability, safer operation, and cost efficiency are important.
- Emerging and custom energy systems- Macsen Energy is open to custom material development for specific sodium-ion cell formats, chemistries, and application requirements.
Scaling Prussian White Technology
Macsen Energy’s scale-up roadmap is designed to move Prussian White from a lab-validated cathode material to a commercially relevant sodium-ion battery technology.
- Macsen Energy has allocated 10,000 sq meters of land for a dedicated scale-up facility for Prussian Blue Analogue cathode materials and a pilot line for cell fabrication. The facility will support the transition toward tonne-level production capacity. Construction of this facility is planned to begin in 2027.
- In 2027, Macsen Energy also plans to establish a sodium-ion battery pilot line within the same site to further optimize Prussian White-based cell technology. This setup will support electrode preparation, cell assembly, full-cell validation, process reproducibility, and performance testing under conditions closer to commercial manufacturing.
- Macsen Energy has also initiated Hard Carbon synthesis R&D to strengthen its full-cell development program.
Go deeper into the chemistry
Download our Prussian White concept paper for the full technical case – synthesis, mechanism, comparative performance, and cost economics.
Evaluating Prussian White for your application?
Speak directly with our R&D and commercial team for material supply, joint development, or complete cell technology partnerships.