August 4th news, Group1 Corporation announced the launch of the world's first KIB potassium-ion battery featuring a 18650 cylindrical casing. The company stated that its new potassium-ion battery can be seamlessly integrated into the existing LIB lithium-ion battery production process, offering a sustainable and cost-effective alternative to traditional lithium-ion batteries.

Working Principle of Potassium-Ion Batteries

Alexander Girau, CEO of Group1 Corporation, stated that this new battery, after years of development, has shown excellent performance. It boasts an impressive cycle life, maintaining a high capacity after numerous charge and discharge cycles, which is crucial for applications such as electric vehicles. Additionally, the battery has strong discharge capabilities, effectively providing power when needed.

According to the introduction, this battery utilizes Group1 Corporation's 4V Prussian white potassium (KPW) cathode material named Kristonite, offering a more balanced performance, safety, and cost compared to lithium iron phosphate batteries (LFP-LIB) and sodium-ion batteries (NIB).

The company mentioned that this potassium-ion battery adopts the same size specifications as the widely used 18650 lithium-ion battery, with a diameter of 18 millimeters and a height of 65 millimeters, allowing seamless integration into existing devices and applications.

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The battery operates at a nominal voltage of 3.7V, ensuring compatibility with modern electronic devices and systems. Moreover, the battery's energy density can reach 160-180Wh/kg, comparable to lithium iron phosphate batteries.

It is also worth mentioning that this potassium-ion battery uses commercialized graphite anodes, separators, and electrolyte formulations, reducing the complexity of the supply chain and decreasing the reliance on key minerals such as nickel, cobalt, copper, and lithium.

Group1 Corporation has already begun distributing samples of this potassium-ion battery to partners among original equipment manufacturers and battery manufacturers, hoping it can become a strong alternative to lithium iron phosphate batteries and sodium-ion batteries.

In fact, the working principle of potassium-ion batteries is similar to that of lithium-ion and sodium-ion batteries, following the "rocking chair" principle, where potassium ions undergo reversible migration between the electrodes during charging/discharging.

The core components of a potassium-ion battery include the cathode, anode, electrolyte, and separator. Both cathode and anode active materials can be coated on aluminum foil, with a separator between the cathode and anode to prevent short circuits. The electrolyte is often an organic solution mixed with potassium salts, with common potassium salts including potassium hexafluorophosphate (KPF6), and common solvents including ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC).During the charging process, potassium ions detach from the positive electrode material and move towards the negative electrode side through components such as the separator and electrolyte, embedding themselves into the negative electrode material. At this time, the positive electrode material is in a potassium-depleted state, while the negative electrode material stores energy by embedding potassium ions. Simultaneously, the energy provided by an external power source (electrical energy) is converted and stored in the battery in the form of chemical energy. Taking manganese-based materials as an example, during charging, the manganese-based material at the positive electrode reduces potassium manganate to oxidized manganese with a positive charge, while potassium ions in the electrode diffuse outward and form a solution.

During the discharging process, potassium ions detach from the negative electrode material, move towards the positive electrode side through the separator and electrolyte, and embed themselves into the positive electrode material. At this time, the positive electrode material regains potassium ions, returning to a potassium-rich state, and releases the stored energy. Simultaneously, the conversion of chemical energy to electrical energy is achieved. In this process, to maintain charge balance during charging and discharging, the number of electrons transferred through the external circuit during the reaction should be the same, maintaining a certain potential.

The charging and discharging process of potassium-ion batteries is essentially a reversible diffusion process of potassium ions between the positive and negative electrode materials, and it is also an energy conversion process between electrical and chemical energy. During charging, electrical energy is converted into chemical energy and stored in the battery; during discharging, chemical energy is converted back into electrical energy and released.

Advantages and Research Progress of Potassium-Ion Batteries

Nowadays, lithium-ion batteries have been widely applied and are very mature. Why is there a need to study potassium-ion batteries? Firstly, potassium is relatively abundant in the Earth's crust, far exceeding lithium, and the cost of mining and processing is relatively low. This gives potassium-ion batteries a significant advantage in raw material costs, which helps to reduce the overall manufacturing cost of batteries and improve the sustainability of the industry.

In addition, compared to lithium-ion batteries, potassium-ion batteries have characteristics of high energy density, which means longer endurance and smaller battery volume, which is particularly important for mobile applications such as electric vehicles; a high working voltage window, which means they can operate over a broader voltage range, improving battery performance and stability; and fast charging and discharging capabilities, as the migration rate of potassium ions in the electrolyte is relatively fast, making potassium-ion batteries suitable for applications requiring fast charging and discharging.

Compared to lithium-ion batteries, potassium-ion batteries also have certain safety advantages. The melting point of metallic potassium is much lower than that of metallic lithium and sodium, so the mechanical properties of potassium dendrites are much weaker, and the formation of potassium dendrites can be reduced by controlling the temperature, lowering safety hazards. Moreover, potassium-ion batteries also show good stability under extreme conditions such as overcharging and over-discharging.

In addition to Group 1 companies, domestic enterprises and institutions have also made progress in the research of potassium-ion batteries. In July of this year, it was reported that Anhui Guoxin New Material Co., Ltd., in collaboration with the State Key Laboratory of New Materials for Material Composite and Advanced Technology at Wuhan University of Technology, successfully developed the world's first commercially available potassium-ion battery product based on electron/ion dual-continuous transport energy storage materials and multi-scale regulation technology for devices.

The battery has advantages such as high energy density (cell energy density of 151Wh/kg), long endurance (a full charge can last 130 to 150 kilometers, about three times that of lead-acid batteries), and low cost (basically equivalent to the production cost of lead-acid batteries). It is expected to gradually replace lead-acid batteries used in two-wheeled electric vehicles in the future and be widely applied in other fields.

The small-scale potassium-ion energy storage system developed by Anhui Guoxin New Material Co., Ltd. has been demonstrated in several projects, and the potassium-ion battery pack has also been tested on electric bicycles. The company expects to achieve mass production of key electrode materials, cells, and energy storage systems for potassium-ion batteries by the end of this year, which will lay a solid foundation for the commercial application of potassium-ion batteries.Anhui Guoxin New Materials Co., Ltd. was established in 2021, primarily focusing on technological research and development around new energy and new materials. The State Key Laboratory of New Materials Composite Technology at Wuhan University of Technology is an important research institution in China in the field of materials science, dedicated to the research and development of new materials composite technologies.

In conclusion, potassium-ion batteries, due to the abundance and stability of the potassium element, offer more advantages in industrial production and large-scale applications. Moreover, potassium-ion batteries also have the advantages of high capacity, high charging and discharging efficiency, and good safety, making them one of the trends for future development. They are particularly suitable for applications in the fields of energy storage and electric vehicles.

However, despite this, potassium-ion batteries still face some technical challenges, such as the larger radius of potassium ions leading to higher requirements for electrode materials; the cycle life and energy density still need to be improved. Therefore, the research on potassium-ion batteries requires continuous exploration of new electrode materials, electrolytes, and battery structures, and other key technological areas, in order to achieve breakthroughs in performance and cost reduction.