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How do you tame the water inside a Prussian White cathode to unlock its true performance?

Prussian White cathodes, a promising material for sodium-ion batteries, contain water within their crystal structure. This water is detrimental to electrochemical performance, and its removal is necessary to trigger a crucial phase transition from the less desirable monoclinic phase to the high-performance rhombohedral phase. This dehydration process is a critical step in unlocking the material's full potential.

Using in-situ X-ray diffraction, the team identified the key parameters for this dehydration. They found that while a temperature of around 170°C is needed, the duration of drying (up to 48 hours) and, critically, the vacuum pressure are essential for a successful phase transition. A higher vacuum (10⁻³ mbar vs. 10⁻² mbar) allows for a more complete transition at lower temperatures, enabling processing at a more manageable 150°C at the electrode level.

The dehydrated rhombohedral phase is highly sensitive to moisture and will quickly reabsorb water from the ambient air, reversing the beneficial phase change. To overcome this while still using a sustainable water-based slurry process, the team developed a clever manufacturing strategy. They process the stable, hydrated monoclinic phase in water to create the electrode, and only then perform the critical dehydration step on the finished electrode under optimized vacuum and temperature conditions.

In this short video, you can learn:
* The critical role of water in the crystal structure of Prussian White cathodes.
* How temperature, time, and vacuum pressure influence the material's dehydration and phase transition.
* A practical manufacturing strategy to enable water-based processing of this moisture-sensitive material.
📋 **Clip Abstract** This clip details the critical challenge of removing structural water from Prussian White cathodes to achieve the high-performance rhombohedral phase. Dr. Hasa explains how her team optimized the dehydration process and developed a manufacturing workaround to enable sustainable, water-based electrode coating.
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Can sodium-ion batteries be a "drop-in" replacement for lithium-ion manufacturing, and what energy density can they realistically achieve?

A key advantage of sodium-ion technology is its compatibility with existing lithium-ion battery manufacturing infrastructure. Dr. Hasa demonstrates this by showcasing the scale-up of their Prussian White/hard carbon cells at the WMG facility. The entire process, from slurry mixing in a one-liter mixer to electrode coating and cell assembly, utilizes standard equipment, confirming that sodium-ion is a true "drop-in" technology that doesn't require a complete overhaul of production lines.

The research successfully transitioned from small, lab-scale coin cells to industrially relevant multi-layer pouch cells with a target capacity of one amp-hour. This scale-up is a critical step in demonstrating the commercial viability of the technology and allows for a more accurate assessment of real-world performance metrics. It proves that the promising results seen at the materials level can be translated into a practical cell format.

By analyzing these 1 Ah pouch cells, the team initially achieved a practical energy density of 120 Wh/kg. Through cell design optimizations—rather than fundamental material improvements—this was later pushed to 160 Wh/kg. Extrapolating from the active material properties alone, the chemistry shows potential for 220 Wh/kg and 420 Wh/L, highlighting a clear path for future improvements through engineering and optimization.

In this short video, you can learn:
* How sodium-ion cells can be produced on existing lithium-ion manufacturing lines.
* The process of scaling up from lab-scale coin cells to 1 Ah pouch cells.
* The achieved (120-160 Wh/kg) and potential (220 Wh/kg) energy density of this chemistry.
📋 **Clip Abstract** Dr. Hasa discusses the successful scale-up of sodium-ion pouch cells, confirming the technology's "drop-in" compatibility with existing Li-ion manufacturing lines. She presents the achieved energy density of 120-160 Wh/kg for their 1 Ah cells and outlines the future potential of the Prussian White/hard carbon chemistry.
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