[SMM Analysis] Prussian White: A Niche Yet Extraordinary Material. How Does It Maintain Competitiveness with Low Cost?

SMM News on June 18:

Driven by the goal of carbon neutrality, sodium-ion batteries have emerged in the fields of energy storage and start-stop applications due to their abundant resources and low cost. Among the three major cathode routes for sodium-ion batteries, the Prussian route is gradually gaining attention. Currently, Prussian materials are divided into Prussian blue and Prussian white. The main reason for the color difference between the two cathodes lies in the crystalline water. Prussian white requires further dehydration based on Prussian blue, necessitating precise control over crystalline water.

I. Characteristics and Working Principle of Prussian White

Prussian white, chemically known as sodium iron cyanide, possesses a unique open-framework structure. This structure provides a spacious and low-resistance transmission channel for sodium ions, enabling rapid intercalation and deintercalation during charging and discharging, and granting the battery excellent rate performance, i.e., the ability to rapidly charge and discharge at high currents. Meanwhile, its constituent elements, iron and sodium, are widely available and cost-effective, laying an economic foundation for the large-scale commercialization of sodium-ion batteries.

II. Performance Advantages

(I) High Specific Capacity

The theoretical specific capacity of Prussian white reaches 155mAh/g. In practical applications, through technological optimization, the specific capacity of its mass-produced materials can reach around 155mAh/g. Prussian white batteries have a relatively high energy density, extending battery life and meeting the high energy density requirements of long duration energy storage (LDES) power stations.

(II) High Cycle Stability

Thanks to its stable structure, Prussian white can maintain good performance after multiple charge-discharge cycles. According to relevant materials, when cycled at a 1C rate, its capacity retention rate is ≥90%, ensuring a long battery lifespan, reducing replacement costs, and enhancing system economy and reliability. This advantage is particularly evident in energy storage scenarios with frequent charge-discharge cycles.

(III) Wide Temperature Adaptability

Prussian white maintains stable performance within the temperature range of -20℃ to 60℃, with no significant degradation. It can adapt to temperature differences in different regions and changes in ambient temperatures without requiring a complex thermal management system. Whether in the cold winters of the north or the hot summers of south China, Prussian white batteries can still operate normally, reducing system costs and maintenance difficulties.

(IV) High Safety

Prussian white exhibits excellent thermal stability, making it less prone to thermal runaway due to overheating. Its chemical properties are stable, and it is difficult for it to react violently with electrolytes, fundamentally reducing the risk of battery combustion and explosion, providing a safety barrier for battery use. Its high safety is particularly valuable in energy storage facilities and EVs in densely populated areas.

III. Technological Breakthroughs and Industrialisation Progress

Currently, there are still relatively few domestic enterprises producing Prussian white. Wenzhou Sodium New Energy Technology Co., Ltd. has achieved remarkable results in the R&D of Prussian white. The company has optimized the preparation technology for monocrystalline Prussian white, overcoming the challenge of precise control over crystalline water, achieving accurate control of crystalline water content, enhancing material crystallinity and purity, and improving electrochemical performance. Currently, the company's production line with an annual output of 1,200 mt of Prussian white commenced operations in October 2024. The planning for a 10,000-mt-scale capacity is steadily advancing. Leveraging the experience from its 100-mt pilot line, the company's production process is simplified, costs are controllable, and safety performance is outstanding. It has emerged as a notable player in the sodium-ion battery industry ecosystem, forming strategic partnerships with multiple top-tier enterprises to assist battery cell customers in developing high-performance sodium-ion batteries. Its products are widely applied in fields such as two/three-wheelers, low-speed four-wheelers, start-stop power supplies for automobiles/motorcycles, energy storage systems, and special power supplies, driving the development of the new energy industry and the transition to green and low-carbon practices.

IV. Application Prospects

Prussian white holds broad application prospects across various fields. In energy storage systems, its high cycle stability and wide temperature adaptability ensure long-term stable operation of ESS power stations, reducing maintenance and replacement costs. In the start-stop field, its performance advantages can optimize battery performance, enabling high C-rate and long cycle life for start-stop power supplies. In the future, with technological advancements and capacity expansions, Prussian white is expected to become one of the important cathode materials, driving the vigorous development of the sodium-ion battery industry and contributing to the global energy transition.

As a cathode material for sodium-ion batteries, Prussian white has emerged in the new energy sector due to its advantages such as high specific capacity and high cycle stability. With technological breakthroughs and the advancement of industrialisation, its application prospects will become even broader, contributing to the realization of green and low-carbon practices and sustainable energy development.

SMM New Energy Research Team

Wang Cong 021-51666838

Ma Rui 021-51595780

Feng Disheng 021-51666714

Lü Yanlin 021-20707875