From Lithium to Battery: Sustainable Battery Production for the Energy Transition
3/4/2024 Energy and raw material base in transition Article

From Lithium to Battery: Sustainable Battery Production for the Energy Transition

Dozens of new battery factories in Europe and the USA, billions invested in production processes: E-mobility, but also the storage of surplus renewable energy in batteries, is currently electrifying the whole of society. But how are batteries made in the first place?

Black and gold battery against a red background
Mixing, coating, assembling, packaging - done. Actually, the production of a battery is quite simple. But the devil is in the detail: in order to be able to store as much energy as possible in the smallest possible space, enormous technological feats are necessary. And that starts with the battery materials.

When the public talks about electromobility or electricity storage in domestic PV installations, almost everyone thinks of lithium-ion batteries - and is usually right. But the storage market is now much more differentiated - the number of battery chemistries is growing steadily. Lithium-ion technology already exists in various forms: The most widespread is the NMC622 variant. The numbers stand for the ratio of the cathode materials nickel, manganese and cobalt; NMC811 is another variant. The lithium iron phosphate battery (LFP) is also important. Although it does not achieve the same energy density as the aforementioned batteries, it allows more charging cycles and does not require the expensive and often problematic metal oxides.

An alternative to this, which has recently made headlines, is the sodium-ion battery (Na-ion), which on the one hand is cheaper than Li-ion cells and which also delivers its power over a wider temperature range. On the other hand, Na-ion batteries have a lower energy density, i.e. they are heavier with the same capacity. And the Na-ion battery also comes in different variants. The main three are based on either "Prussian white" - a complex inorganic compound -, metal oxide layers with nickel, manganese and others, and so-called polyanion cathodes. And to make the confusion complete: There are many more chemical combinations capable of storing electrical energy.

Four steps lead to the battery

In manufacturing, the material differences are less relevant: The production lines of the gigafactories can be converted relatively quickly from Li-ion to Na-ion, for example. This is because the construction is basically the same: the batteries consist of the four core elements cathode, anode, separator and electrolyte. The most important process steps in the production are:
  • Electrode production
  • Cell assembly
  • Formation
  • Aging
Both cathodes and anodes consist of the active material - graphite for anodes, e.g. lithium cobalt oxide for cathodes -, conductive carbon black, solvent, binder and additives, each of which is combined into a homogeneous paste (slurry) by intensive energy input in mixers, dispersers or extruders. Depending on the electrode design, dry mixing or wet dispersion is carried out in different sequences. Then a carrier foil - copper for anodes, aluminium for cathodes - is coated with the slurry and then dried. The subsequent calendering ensures a homogeneous layer thickness of the electrodes.

After the electrode strip has been cut, the rolled coils are dehumidified in vacuum dryers. This is followed by cell assembly, in which the electrode is either folded into cell stacks (pouch) or rolled (round cell, prismatic cell). After the arrester foils are contacted, the electrodes are placed in the packaging and finally filled with electrolyte.
In the formation process step, the battery cells are charged and discharged for the first time, whereby lithium ions are deposited in the graphite structures of the anode. The subsequent aging aims to identify any short circuits in the cells. Each of these process steps has a greater or lesser influence on the performance and safety of the battery.

Great potential for improvement in processes and technology

The complexity of battery production is also increasing due to external market developments: Sharply rising lithium and nickel prices are forcing manufacturers to adapt their formulations and technologies. New technologies, such as the replacement of liquid electrolytes by solid or semi-solid electrolytes, but also faster mixing processes could lead to new disruptions. This is also where the opportunity lies for European manufacturers with regard to Chinese dominance.

In order not to miss these opportunities, new battery factories are often already being built for processes that have not even been developed yet. This puts pressure on machine suppliers: parallel to the construction of the Gigafab, they often have to develop feeding, dosing and mixing processes in painstaking empirical detail work so that the required qualities and performance are finally achieved. And scaling up from the laboratory and pilot plant to large-scale production is another challenge. A current example: Up to now, the active materials have mostly been delivered in big bags. Emptying several dozen of such big bags by hand or semi-automatically is inefficient - new logistics processes could lead to significant improvements here, especially if the distances between the manufacturers are short and the supply chains are integrated.
Machines specially adapted to the requirements of battery production, such as pumps and transport systems that convey abrasive slurries, machines and interfaces that safely achieve the required workplace limits (OEB 4 and 5), but also test systems and analytical equipment for these special requirements are among the challenges that many equipment suppliers face. And this will also be on display at the upcoming POWTECH TECHNOPHARM, which will take place in Nuremberg from 23 to 25 September 2025.