Grinding and rounding for batteries and fuel cells
How efficiently electrical energy can be stored and provided in batteries and fuel cells depends in particular on the quality of the raw materials used in their manufacturing process.
A key raw material, both for the anodes of Li-ion batteries and bipolar plates in fuel cells, is carbon, made from natural graphite or in form of synthetic graphite based on petroleum coke. In Li-ion batteries, silicon, which is currently added at only 4-8% to increase battery capacity and shorten charging cycles, is also gaining importance. The goal is to allow for an increased proportion of silicon in the anode material, optimize the battery performance. Especially important is such a performance increase for use in electric vehicles (EV) and eventually even replacing today's Li-ion batteries with so-called lithium silicon batteries.
For use in batteries or fuel cells, the raw materials e.g. green coke, synthetic or natural graphite and silicon must have special properties. Decisive factors in the comminution and rounding are therefore
- Fine but steep particle size distributions
- Highest possible tap density
- Maximum Specific BET surfaces
- Particle shape as round as possible
Separate grinding and rounding of raw materials for batteries and fuel cells
If the grinding and rounding is done in one process, large losses occur, which can account for up to 70% of the raw material. For this reason, NEUMAN & ESSER Process Technology has developed a solution, which separates the process into grinding and rounding. The impact classifier mill eXtra ICX and the spheronizer ICS were specifically designed for this purpose.
Steep particle size distribution and finest particles with the NEUMAN & ESSER ICX:
In order to produce fine particles with a steep particle size distribution, i.e. a small proportion of so-called "superfines", the NEUMAN & ESSER impact classifier mill ICX can be used for ultrafine applications. Due to the unique air and particle guidance as well as the highly efficient integrated classifier module, the material is ground to the desired fineness on this mill, but not overground. For battery applications the fineness requirements are often in the range of 90% < 10-40 µm.
High tap densities and steep particle size distributions due to rounding on the NEUMAN & ESSER ICS:
In graphite, the increase in energy density is mainly achieved by increasing the sphericity of the particles and thus a higher packing density.
Due to tools specifically designed for this purpose and the highly efficient integrated classifier module for ultra-fine classifying, the ICS allows the complete spheronizing of particles in a single step. This rounding is possible for green coke before graphitization as well as for synthetic and natural graphite.
The spheronizing process on the NEA ICS is characterized by both the high tap densities > 1000g/l and the high yields of 70-85%.
In addition, undesirable fines can be specifically removed from the product by varying the classifier speed. This allows for even steeper particle size distributions and higher tapping densities.
Adaption of the particle size distribution by the NEUMAN & ESSER GRC:
The NEA GRC guide ring classifier offers a further possibility for the targeted modification of a particle size distribution in the fine and coarse range. This classifier is used, among other things, to separate specific ultra-fine fractions in order to achieve steep particle size distributions. This process offers the advantage that the finest fraction can be reused either by blending or in applications with other products. This increases the overall yield.
Petroleum Coke (precursor of synthetic graphite)
Natural Graphite
Energy turnaround through the efficient use of batteries and fuel cells
To counteract climate change by massively reducing CO2 emissions, many countries around the world are implementing an energy turnaround. According to the International Renewable Energy Agency (IRENA), up to 90% of the required CO2 savings can be achieved through renewable energies and measures increasing energy efficiency.
A major challenge in energy transformation is the efficient storage and provision of renewable energies, which are not always universally available. Batteries and the hydrogen fuel cell are of particular importance in solving this task.
Manufacturers of batteries and fuel cells want to promote the energy turnaround with the following measures:
- Increasing energy density and storage capacity
- Optimizing of the charging cycles
- Increasing the efficiency of energy transmission
- Increasing of the service life