Only a humming noise can be heard when an electric car accelerates. Quietly, but unstoppably, electro-mobility is picking up speed worldwide. Not audible at all, but at least just as important: no exhaust gases harm the environment – if the electricity used for ‘refuelling’ is produced from renewable energy.
It is a market of the future: in 2015, 550,000 purely electric vehicles and around twice as many hybrid vehicles were registered worldwide. Demand is growing, vehicle manufacturers are booming and hence battery producers too, because the batteries, alongside the electric motor, are the heart of the e-car. Around 30 to 40 per cent of the added value on purely electric vehicles is accounted for by the battery.
New factories are being built across the world and automation is in high demand: from the production of the electrodes and the cell through to the assembly of the battery module. Among other things, standard handling systems are used, which must not damage or contaminate the sensitive lithium-ion cells during the production process. The production environment of lithium-ion batteries poses further special challenges for automation technology: it must be clean and have low humidity.
One of the major challenges is foreign metals, especially copper. The precious metal is a key alloy component of brass leads, as used, for example, in electric drives. Due to friction, abraded particles in tiny amounts can get into the environment. If copper particles contaminate the surface of electrodes, even the smallest quantities can lead to an unwelcome chemical reaction in the battery. Tiny needles are formed, which damage the sensitive separator membrane inside the battery and can trigger a short circuit. The second challenge is air humidity: if the electrolyte, in other words the fluid in the battery, which is used to store energy, absorbs moisture from the air, this reduces its performance significantly.
Dry room for manufacturing
It does not have to be a clean room, however. For the production of lithium-ion batteries, a so-called dry room is sufficient, where the air is permanently treated and where copper-free automation components are used. Many Festo products are copper-free as standard, for example when the leads are made of plastic materials. The alloy content of copper in the metals is less than six per cent at Festo. In addition, since 2017 Festo has been supplying special components on which all the parts that generate friction are free of copper – for example the guide bearings. Even higher standards are not a problem either: if a battery manufacturer does want to be on the safe side and produce batteries under clean room conditions, Festo’s standard market products fulfil the ISO6/ISO7 clean room conditions as a rule.