S&L's Comprehensive Guide to Dryer and Mixer for Lithium-ion Battery Cathode Materials

In our previous article, we delved into the equipment associated with anode materials for lithium-ion batteries. Today, we shift our focus to the essential equipment utilized in the production of cathode materials, a crucial component of lithium-ion batteries that power new energy vehicles.

Cathode Materials: The Heart of Lithium-ion Batteries

Cathode materials play a pivotal role in lithium-ion batteries, forming the core of the power source for new energy vehicles. There are mainly three types of cathode materials: Lithium Iron Phosphate (LFP), Lithium Manganate (LMO), and Ternary Lithium Batteries.

LFP, as a cathode material, boasts several advantages such as a long cycle life, excellent safety performance, and relatively low manufacturing costs. However, it has a drawback of lower energy density. Ternary Lithium Batteries, on the other hand, are composed of a specific proportion of Nickel-Cobalt-Aluminum (NCA) or Nickel-Cobalt-Manganese (NCM). Thanks to their high energy density, they have become the preferred choice for a majority of new energy vehicles, with approximately 60% of cars being equipped with them. By the end of 2018, the energy density of Chinese Monolithic Cells had reached 265Wh/kg. In 2019, CATL launched the 811 Ternary Lithium Batteries, achieving an impressive energy density of up to 304Wh/kg. This high energy density has enabled mainstream electric vehicles to achieve a mileage of over 400 km, and some models can even reach up to 500 km, effectively alleviating the range anxiety of electric vehicle users.

The Cathode Material Industry Chain

The upstream of the cathode material industry chain consists of mineral raw materials like lithium, cobalt, and nickel, along with other related minerals. These raw materials are combined with conductive agents and binders to produce precursors. Through a specific synthesis process, these precursors are transformed into cathode materials suitable for various applications. The following is a detailed structural diagram that illustrates the entire cathode material industry chain.

General Preparation Methods

Solid Phase Synthesis

This method typically involves grinding and mixing lithium salts such as Lithium Carbonate with cobalt or nickel compounds. Subsequently, the mixture proceeds to the sintering reaction stage. While it is relatively simple and the raw materials are easily accessible, which made it popular in the early development of lithium batteries, it has certain limitations. These include limited capacity, poor mixing uniformity and stability, and inconsistent quality between batches.

Complex Method

In this approach, organic complexes are employed to prepare complex precursors containing lithium ions, cobalt, or vanadium ions, followed by sintering reactions. The advantages of this method are a better mixing effect, enhanced uniformity and stability, and a higher capacity compared to the solid phase method.

Sol-gel Method

Originating from the method of preparing ultrafine particles developed in the 1970s, the Sol-gel method is used to produce cathode materials. In addition to the benefits of the complex method, it significantly improves the capacitance of the prepared electrode materials. As a result, it has been experiencing rapid development both domestically and internationally.

Ion Exchange Method

The LiMnO2 prepared through the ion exchange method exhibits a reversible discharge capacity of 270mA•h/g, making it a new area of research interest due to its stable electrode performance and high capacity. However, its practical implementation is currently challenging due to time-consuming and energy-intensive steps such as recrystallization and evaporation.

Production Process

The following chart depicts a typical production process for cathode materials. S&L plays a vital role by providing mixing equipment for the stage before the first sintering, difference batch mixers for the finished product, and even plough paddle dryers during the production of high nickel cathode materials.

Equipment Selection

Plough Mixer -LDH Series

The Plough Mixer is an indispensable choice for mixing lithium battery materials, especially ternary precursors. It consists of a cylindrical body, a plough agitator, a chopper assembly, a drive system, and a discharge valve. With the assistance of high-speed choppers that break up lumps, the material undergoes a centrifugal convection movement during high-speed mixing, achieving excellent mixing homogeneity in a short period.

Advantages:

High Efficiency: Short mixing time ensures increased productivity.

Easy Maintenance: Convenient for cleaning and upkeep.

Specialized Design: High-speed chopper tailored for lithium battery applications.

Isolation: Wear-resistant ceramic ploughs or tungsten carbide coating to separate lithium battery materials from metal ions.

Durability: Wear-resistant vessel with a ceramic lining inside the mixer body for further isolation.

Sealing: Special seals for the main shaft and choppers designed specifically for the lithium battery industry.

Customization: Customized discharge valve options available for the lithium battery industry.

Plough Paddle Dryer-LPH Series

The drying process is crucial in the production of high nickel products. By adding a heating jacket, vacuum design, and dust filter to the original plough mixer, the wet material can form a convection mixing along the cylinder wall, ensuring uniform heating within a specific time frame. The mixer body is made of wear-resistant titanium material, which is also corrosion-resistant, guaranteeing product quality. It can also be equipped with a mature blowback filter.

Ribbon Mixer- WLDH series

The Horizontal Ribbon Mixer is widely utilized to minimize batch mixing differences in the final product. Comprising a special U-shaped body, ribbon mixing elements, a driving system, and a discharge valve, the outer ribbon pushes materials from the two ends towards the center, while the inner ribbon moves the materials from the middle to the two ends. This creates a convection movement that ensures perfect mixing homogeneity.

Advantages:

Gentle Mixing: Soft mixing to prevent damage to the physical properties of the material.

Structural Options: Multiple choices for the mixer body structure, including U-shaped, droplet, and cylinder shapes.

Ion Isolation: Double ribbons with tungsten carbide coating to isolate lithium battery materials from metal ions.

Leak Prevention: Special main shaft seal designed to prevent material leakage.

User Cases

Since 2018, S&L Group has been in close cooperation with SHANSHAN Technology, continuously supplying equipment for both anode and cathode materials, including the GBF reactor, horizontal ribbon mixer WLDH, and plough mixer LDH. Through this partnership, S&L has developed a comprehensive set of mixing solutions for lithium battery cathodes, such as ceramic lining of the mixer body, tungsten carbide coating of the agitator, mechanical seal of the main shaft, and professional drive system design.

Looking to the Future

After years of serving industry leaders like Umicore, LG, SK, Ronbay, Shanshan, Changyuan LICO, and others in the lithium battery industry with high-quality and efficient mixing equipment, S&L has successfully overcome numerous challenges. As a result, it has acquired in-depth knowledge of the core technology and material characteristics involved in the production of lithium battery raw materials, positioning itself for continued success in the evolving lithium battery market.