Saving energy and costs in the production of battery masses

The more the electrification of mobility and other sectors progresses, the greater the demand for lithium-ion batteries. For the energy-intensive production of battery masses, the boom means that ever larger capacities are required. How do manufacturers achieve the highest possible energy efficiency? Netzsch has compared various grinding systems in a test to offer operators the best solution.

Written by Marius Schaub

There are various grinding systems for processing lithium iron phosphate (LiFePO4) as battery material, which can be used depending on the specific requirements. Among the wet grinding systems, pin mills and disk mills are particularly relevant for this application. The choice of grinding system depends on various factors, including the desired particle size, the production capacity, and the specific properties of the LiFePO4 material.
The evaluation of the various systems in terms of their energy consumption is particularly challenging, but equally interesting from a manufacturer's perspective. As a physical process, the grinding of materials is very energy-intensive: the higher the energy input, the better the result typically is. In addition, the demand for battery mass for the production of lithium-ion cells will continue to rise sharply in the foreseeable future, mainly due to the growing importance of electromobility. Cost savings through the lowest possible energy consumption in production are correspondingly scalable. The aim is therefore to find the perfect balance between efficiency and cost-effectiveness.
Netzsch carried out a field study to support a customer in their search for the best grinding system for their requirements. It was intended to answer the question of which technology is the right one for this application.

Illustration of a pin grinding system with visible interior — Pin grinding systems such as Zeta and Neos from Netzsch are suitable for circulation and multi-passage operation with a wide range of viscosities.

Different grinding systems for different requirements

The main requirements were a planned production volume of 100,000 tons per year and a particle size of 380 µm for the end product. The customer also had precise requirements for other process parameters such as the number of machines, the cooling solution, and the energy density. For example, the number of different mills had to be kept as low as possible to minimize the space required for the system. There was also a desire for a simple, flexible, and reliable process for which as few spare parts as possible had to be kept in stock.
Two of the manufacturer's grinding methods were tested: the Zeta and Neos pin grinding systems and the Discus disk mill. The classic disk mill has a high length-to-diameter ratio. Recirculation operation is common for such a system. With their short length and large diameter, disk mills are mainly used for recirculation operation.
Pin grinding systems offer a high energy input with a correspondingly high energy density. The technology enables the use of smaller grinding media, which increases the possible production capacity: Faster operation offers faster results.
The varying grain sizes to be expected in the starting material spoke in favor of circulation operation. The suspension is fed back through the mill into the tank, where the already ground suspension is mixed with the suspension that has not yet been ground. This continuously increases the quality of the product; as soon as the defined properties are reached, the process is stopped.

Illustration of a disk mill with visible interior — Horizontal disk mills are based on proven technology and offer particularly high productivity.

Field study with surprising results

The impressive result of the tests: In order to achieve the desired grain size, around three times the amount of energy was required for pre-grinding with a disk mill. The figures are all the more surprising given that Netzsch would have originally relied on a disk grinding system for the defined process conditions. Scaled to the intended production volume, the difference in energy consumption means a difference of 1.7 million euros per year. In addition, only 9 disk mills instead of 21 pin mill systems are required for the annual production volume.
Great savings potential was also identified in the final ultrafine grinding in recirculation mode: By slightly reducing the energy density and processing speed, the energy consumption of this process step could be reduced by a good third.
The bottom line is that the customer can look forward to considerable cost savings as a result of the study: according to Netzsch’s calculations, the entire grinding process will be 7.7 million euros cheaper per year. The conclusion of the field study: it is not always necessary to run processes with the highest energy density. It is always worth examining the material to be processed and focusing on its properties.

Author

Marius Schaub